191 (number)

191 (one hundred [and] ninety-one) is the natural number following 190 and preceding 192.

← 190 191 192 →
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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
Octal	2778
Duodecimal	13B12
Hexadecimal	BF16

In mathematics

• 191 is an odd number
• 191 is a centered 19-gonal number[1]
• 191 is a deficient number, as 1 is less than 191
• 191 is a lazy caterer, number of slices a circle can be made into (19 slices can divide into 191 pieces)
• 191 is an odious number
• 191 is a prime number
  • Chen prime
  • Eisenstein prime with no imaginary part
  • Gaussian prime
  • Palindromic prime, in base 10
  • Part of a prime quadruplet of four primes: 191, 193, 197, and 199
  • Sophie Germain prime
  • Strong prime
  • Twin prime that differs from another prime number (193) by 2
  • 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.[2]
• 191 is a square-free number
• 191 is a Thabit number
• 191 is an undulating number
• 191 is the smallest positive integer d such that the imaginary quadratic field Q(√–d) has class number = 13.[3]

In astronomy

• 191 Kolga is a large and dark Main belt asteroid
• 3C 191 is a quasar located in the constellation Cancer

In geography

• 191 Peachtree Tower at 191 Peachtree Street is the fourth tallest skyscraper in Atlanta
• 191 North Wacker is a 37-story skyscraper in Chicago
• Marquis No. 191, Saskatchewan is a rural municipality in Saskatchewan, Canada

In the military

• 191st Air Refueling Squadron unit of the Utah Air National Guard
• 191st Airlift Group unit the Michigan Air National Guard at Selfridge ANGB, Michigan
• 191st Battalion, CEF was a unit of the Canadian Expeditionary Force in Southern Alberta, Canada
• 191st Infantry Brigade formed as part of the United States Army Reserve's 95th Division
• Focke-Wulf Fw 191 was a prototype German bomber aircraft of World War II
• No. 191 Squadron RAF a Royal Air Force squadron from 1917–1919, and 1943–1945
• Special Order 191 was a military order issued by Confederate Army General Robert E. Lee in the Maryland Campaign of the American Civil War
• USNS Benjamin Isherwood (T-AO-191) is a United States Navy Henry J. Kaiser-class fleet replenishment oiler
• USS Coffman (DE-191) was a United States Navy Cannon-class destroyer escort during World War II
• USS Frigate Bird (AMS-191) was a United States Navy Bluebird-class minesweeper during the 1950s
• USS Lebanon (AK-191) was a United States Navy C1-M-AV1-type cargo ship during World War II
• USS Mason (DD-191) was a United States Navy Clemson-class destroyer during World War II
• USS Pondera (APA-191) was a United States Navy Haskell-class attack transport during World War II
• USS Sculpin (SS-191) was a United States Navy Sargo-class submarine during World War II
• USS Vandalia (IX-191) was a United States Navy a twin-screw, steel-hulled tanker during World War II
• VF-191, "Satan's Kittens", was a fighter squadron of the United States Navy during World War II

In movies

• The 2008 movie “Highway 191”

In transportation

• RD-191, a Russian high performance single-combustion chamber rocket engine
• 191st Street (IRT Broadway – Seventh Avenue Line), a New York City Subway station at St. Nicholas Avenue in Manhattan served by the 1 train
• At least five known plane crashes have involved flights numbered 191; as a result, the number is considered unlucky in the airline industry and has been withdrawn from use in some airlines

In other fields

191 is also:

• The year AD 191 or 191 BC
• The atomic number of an element temporarily called Unennunium
• Minuscule 191 is a Greek minuscule manuscript of the New Testament, on parchment
• Bose Virtually Invisible 191 speakers

See also

• List of highways numbered 191
• United Nations Security Council Resolution 191
• United States Supreme Court cases, Volume 191
• Pennsylvania House of Representatives, District 191

External links

• Number Facts and Trivia: 191
• The Number 191
• Number Gossip: 191
• VirtueScience: 191
• Prime Curios: 191

References

1. "Sloane's A069132 : Centered 19-gonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.
2. Wolfram MathWorld; Primitive Root
3. "Tables of imaginary quadratic fields with small class number". numbertheory.org.