191 (number)
From HandWiki
Short description: Natural number
| ||||
|---|---|---|---|---|
| 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 | |||
| Quaternary | 23334 | |||
| Quinary | 12315 | |||
| Senary | 5156 | |||
| Octal | 2778 | |||
| Duodecimal | 13B12 | |||
| Hexadecimal | BF16 | |||
| Vigesimal | 9B20 | |||
| Base 36 | 5B36 | |||
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
- 191 (disambiguation)
References
- ↑ Sloane, N. J. A., ed. "Sequence A136162 (List of prime quadruplets {p, p+2, p+6, p+8})". OEIS Foundation. https://oeis.org/A136162.
- ↑ Sloane, N. J. A., ed. "Sequence A005384 (Sophie Germain primes p: 2p+1 is also prime)". OEIS Foundation. https://oeis.org/A005384.
- ↑ Wolfram MathWorld; Primitive Root
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