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191 (number)
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191 43rd
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.A136162 List of prime quadruplets {p, p+2, p+6, p+8} Because doubling and adding one produces another prime number (383), 191 is a Sophie Germain prime.A005384 Sophie Germain primes p: 2p+1 is also prime It is the smallest prime that is not a full repetend prime in any base from 2 to 10; in fact, the smallest base for which 191 is a full period prime is base 19.Wolfram MathWorld; Primitive Root
See also
191 (disambiguation)
References
1
Category:Integers
Category:Prime numbers