← 226 227 228 →
Cardinaltwo hundred twenty-seven
Ordinal227th
(two hundred twenty-seventh)
Factorizationprime
Primeyes
Greek numeralΣΚΖ´
Roman numeralCCXXVII
Binary111000112
Ternary221023
Senary10156
Octal3438
Duodecimal16B12

227 (two hundred [and] twenty-seven) is the natural number between 226 and 228. It is also a prime number.

## In mathematics

227 is a twin prime and the start of a prime triplet (with 229 and 233).[1] It is a safe prime, as dividing it by two and rounding down produces the Sophie Germain prime 113.[2] It is also a regular prime,[3] a Pillai prime,[4] a Stern prime,[5] and a Ramanujan prime.[6]

227 and 229 form the first twin prime pair for which neither is a cluster prime.

The 227th harmonic number is the first to exceed six.[7] There are 227 different connected graphs with eight edges,[8] and 227 independent sets in a 3 × 4 grid graph.[9]

## References

1. ^ Sloane, N. J. A. (ed.). "Sequence A022004 (Initial members of prime triples (p, p+2, p+6))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
2. ^ Sloane, N. J. A. (ed.). "Sequence A005385 (Safe primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
3. ^ Sloane, N. J. A. (ed.). "Sequence A007703 (Regular primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. ^ Sloane, N. J. A. (ed.). "Sequence A063980 (Pillai primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
5. ^ Sloane, N. J. A. (ed.). "Sequence A042978 (Stern primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. ^ Sloane, N. J. A. (ed.). "Sequence A104272 (Ramanujan primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
7. ^
8. ^ Sloane, N. J. A. (ed.). "Sequence A002905 (Number of connected graphs with n edges)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
9. ^