191 (number)

In mathematics

• 191 is an odd number
• 191 is a centered 19-gonal number
• 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
• 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 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.
• 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 has class number = 13.

  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
• is a United States Navy fleet replenishment oiler
• was a United States Navy during World War II
• was a United States Navy during the 1950s
• was a United States Navy C1-M-AV1-type cargo ship during World War II
• was a United States Navy during World War II
• was a United States Navy during World War II
• was a United States Navy during World War II
• 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 “”

  In transportation

• RD-191, a Russian high performance single-combustion chamber rocket engine
• 191st Street, a New York City Subway station at St. Nicholas Avenue in Manhattan served by the 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

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