191 (NUMBER)

'191' is the natural number between 190 and 192. It is also a prime number.

Cardinal	One hundred [and] ninety-one
Ordinal	191st
Factorization	prime number
Roman numeral	CXCI
Binary	10111111
Hexadecimal	BF

Contents

In mathematics

In other fields

In mathematics

191 is a prime number, a Sophie Germain prime, a Chen prime and a twin prime with 193. It is also a Thabit number and an Eisenstein prime with no imaginary part. 191 is the index of the Wagstaff prime 1046183622564446793972631570534611069350392574077339085483.
In base 10, it is a palindromic prime.

In other fields

Several aircraft operating under the flight number of 191 have crashed. These include Prinair Flight 191, Delta Air Lines Flight 191, X-15 Flight 191, and American Airlines Flight 191 which was then the most deadly commercial airline crash in US history. Most recently, Comair Flight 5191 crashed on August 27, 2006 in Kentucky. The significance here is that the 5 in 5191 is just a computer designator indicating that it is a connection carrier for Delta Air Lines. In the Comair system and the ATC system, this flight was referred to as 191.