191 (number): Difference between revisions
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==In mathematics== |
==In mathematics== |
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191 is a [[prime number]], part of a [[prime quadruplet]] of four [[prime number|primes]]: 191, [[193 (number)|193]], [[197 (number)|197]], and [[199 (number)|199]].<ref>{{Cite OEIS|A136162|List of prime quadruplets {p, p+2, p+6, p+8} }}</ref> Because doubling and adding one produces another prime number (383), 191 is a [[Sophie Germain prime]].<ref>{{Cite OEIS|A005384|Sophie Germain primes p: 2p+1 is also prime}}</ref> It is the smallest prime that is not a [[full reptend prime]] in ''any'' base from 2 to 10; in fact, the smallest base for which 191 is a full period prime is [[base 19]].<ref>Wolfram MathWorld; [http://mathworld.wolfram.com/PrimitiveRoot.html Primitive Root]</ref> |
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* 191 is an [[Parity (mathematics)|odd number]] |
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* 191 is a [[centered polygonal number|centered 19-gonal number]]<ref>{{Cite web|url=https://oeis.org/A069132|title=Sloane's A069132 : Centered 19-gonal numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-05-28}}</ref> |
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* 191 is a [[deficient number]], as 1 is less than 191 |
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* 191 is a [[Lazy caterer's sequence|lazy caterer]], number of slices a circle can be made into (19 slices can divide into 191 pieces) |
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* 191 is an [[Thue-Morse sequence|odious number]] |
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* 191 is a [[prime number]] |
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** [[Chen prime]] |
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** [[Eisenstein prime]] with no imaginary part |
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** [[Gaussian integer|Gaussian prime]] |
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** [[Palindromic prime]], in base 10 |
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** Part of a [[prime quadruplet]] of four [[prime number|primes]]: 191, [[193 (number)|193]], [[197 (number)|197]], and [[199 (number)|199]] |
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** [[Sophie Germain prime]] |
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** [[Strong prime]] |
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** [[Twin prime]] that differs from another [[prime number]] ([[193 (number)|193]]) by [[2 (number)|2]] |
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** The smallest prime that is not a [[full reptend prime]] in ''any'' base from 2 to 10 – in fact the smallest base for which 191 is a full period prime is [[base 19]].<ref>Wolfram MathWorld; [http://mathworld.wolfram.com/PrimitiveRoot.html Primitive Root]</ref> |
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* 191 is a [[square-free]] number |
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* 191 is a [[Thabit number]] |
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* 191 is an [[undulating number]] |
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* 191 is the smallest positive integer ''d'' such that the imaginary [[quadratic field]] '''Q'''({{sqrt|–''d''}}) has [[Class number (number theory)|class number]] = 13.<ref>{{cite web|title=Tables of imaginary quadratic fields with small class number|website=numbertheory.org|url=http://www.numbertheory.org/classnos/}}</ref> |
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==In astronomy== |
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* [[191 Kolga]] is a large and dark [[Asteroid belt|Main belt]] [[asteroid]] |
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* [[3C 191]] is a [[quasar]] located in the [[constellation]] [[Cancer (constellation)|Cancer]] |
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==In geography== |
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* [[191 Peachtree Tower]] at 191 [[Peachtree Street]] is the fourth tallest [[skyscraper]] in [[Atlanta]] |
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* [[191 North Wacker]] is a 37-story skyscraper in [[Chicago]] |
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* [[Marquis No. 191, Saskatchewan]] is a [[List of rural municipalities in Saskatchewan|rural municipality]] in [[Saskatchewan]], Canada |
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==In the military== |
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* [[191st Air Refueling Squadron]] unit of the [[Utah Air National Guard]] |
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* [[191st Airlift Group]] unit the [[Michigan Air National Guard]] at [[Selfridge ANGB]], [[Michigan]] |
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* [[191st (South Alberta) Battalion, CEF|191st Battalion, CEF]] was a unit of the [[Canadian Expeditionary Force]] in [[Southern Alberta|Southern Alberta, Canada]] |
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* [[191st Infantry Brigade (United States)|191st Infantry Brigade]] formed as part of the [[United States Army Reserve]]'s [[95th Infantry Division (United States)|95th Division]] |
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* [[Focke-Wulf Fw 191]] was a prototype [[Germany|German]] bomber aircraft of [[World War II]] |
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* [[No. 191 Squadron RAF]] a [[Royal Air Force]] squadron from 1917–1919, and 1943–1945 |
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* [[Special Order 191]] was a military order issued by [[Confederate Army]] [[General (CSA)|General]] [[Robert E. Lee]] in the [[Maryland Campaign]] of the [[American Civil War]] |
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* {{USNS|Benjamin Isherwood|T-AO-191}} is a [[United States Navy]] {{sclass-|Henry J. Kaiser|oiler|0}} [[fleet replenishment oiler]] |
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* {{USS|Coffman|DE-191}} was a United States Navy {{sclass-|Cannon|destroyer escort}} during World War II |
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* {{USS|Frigate Bird|AMS-191}} was a United States Navy {{sclass-|Bluebird|minesweeper}} during the 1950s |
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* {{USS|Lebanon|AK-191}} was a United States Navy C1-M-AV1-type cargo ship during World War II |
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* {{USS|Mason|DD-191}} was a United States Navy {{sclass-|Clemson|destroyer}} during World War II |
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* {{USS|Pondera|APA-191}} was a United States Navy {{sclass-|Haskell|attack transport}} during World War II |
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* {{USS|Sculpin|SS-191}} was a United States Navy {{sclass-|Sargo|submarine}} during World War II |
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* {{USS|Vandalia|IX-191}} was a United States Navy a twin-screw, steel-hulled [[Tanker (ship)|tanker]] during World War II |
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* [[VF-191]], "Satan's Kittens", was a fighter squadron of the United States Navy during World War II |
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==In movies== |
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* The 2008 movie “[https://www.imdb.com/title/tt1210348/ Highway 191]” |
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==In transportation== |
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* [[RD-191]], a Russian high performance single-combustion chamber rocket engine |
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* [[191st Street (IRT Broadway – Seventh Avenue Line)]], a New York City Subway station at St. Nicholas Avenue in Manhattan served by the {{NYCS Broadway-Seventh north|time=nolink}} train |
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* At least five known plane crashes have involved [[Flight 191 (disambiguation)|flights numbered 191]]; as a result, the number is considered unlucky in the airline industry and has been withdrawn from use in some airlines |
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==In other fields== |
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''' 191''' is also: |
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* The year [[191|AD 191]] or [[191 BC]] |
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* The [[atomic number]] of an element temporarily called [http://www.flw.com/datatools/periodic/001.php?id=191 Unennunium] |
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* [[Minuscule 191]] is a [[Greek language|Greek]] [[Lower case|minuscule]] [[manuscript]] of the [[New Testament]], on parchment |
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* [[Bose Corporation|Bose]] [http://www.bose.com/controller?url=/shop_online/speakers/stereo_speakers/191_speakers/index.jsp&perfsourceid=k115513&src=k115513 Virtually Invisible 191] speakers |
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==See also== |
==See also== |
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* [[191 (disambiguation)]] |
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* [[List of highways numbered 191]] |
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* [[United Nations Security Council Resolution 191]] |
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* [[List of United States Supreme Court cases, volume 191|United States Supreme Court cases, Volume 191]] |
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* [[Pennsylvania House of Representatives, District 191]] |
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==External links== |
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* [https://web.archive.org/web/20040609064156/http://athensohio.net/reference/number/191/ Number Facts and Trivia: 191] |
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* [http://www.numdic.com/191 The Number 191] |
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* [http://www.numbergossip.com/191 Number Gossip: 191] |
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* [http://www.virtuescience.com/191.html VirtueScience: 191] |
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* [http://primes.utm.edu/curios/page.php?short=191 Prime Curios: 191] |
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== References == |
== References == |
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{{Reflist}} |
{{Reflist}} |
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{{Integers|1}} |
{{Integers|1}} |
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{{DEFAULTSORT:191 (Number)}} |
{{DEFAULTSORT:191 (Number)}} |
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[[Category:Integers]] |
[[Category:Integers]] |
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{{num-stub}} |
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Revision as of 20:51, 30 December 2022
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|---|---|---|---|---|
| Cardinal | one hundred ninety-one | |||
| Ordinal | 191st (one hundred ninety-first) | |||
| Factorization | prime | |||
| Prime | yes | |||
| Greek numeral | ΡϞΑ´ | |||
| Roman numeral | CXCI | |||
| Binary | 101111112 | |||
| Ternary | 210023 | |||
| Senary | 5156 | |||
| Octal | 2778 | |||
| Duodecimal | 13B12 | |||
| Hexadecimal | BF16 | |||
191 (one hundred [and] ninety-one) is the natural number following 190 and preceding 192.
In mathematics
191 is a prime number, part of a prime quadruplet of four primes: 191, 193, 197, and 199.[1] Because doubling and adding one produces another prime number (383), 191 is a Sophie Germain prime.[2] It is the smallest prime that is not a full reptend prime in any base from 2 to 10; in fact, the smallest base for which 191 is a full period prime is base 19.[3]
See also
References
- ^ Sloane, N. J. A. (ed.). "Sequence A136162 (List of prime quadruplets {p, p+2, p+6, p+8})". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A005384 (Sophie Germain primes p: 2p+1 is also prime)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Wolfram MathWorld; Primitive Root
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