227 (number)

	← 220 221 222 223 224 225 226 227 228 229 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	two hundred twenty-seven
Ordinal	227th; (two hundred twenty-seventh)
Factorization	prime
Prime	yes
Greek numeral	ΣΚΖ´
Roman numeral	CCXXVII
Binary	111000112
Ternary	221023
Quaternary	32034
Quinary	14025
Senary	10156
Octal	3438
Duodecimal	16B12
Hexadecimal	E316
Vigesimal	B720
Base 36	6B36

Short description: Natural number

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

↑ Sloane, N. J. A., ed. "Sequence A022004 (Initial members of prime triples (p, p+2, p+6))". OEIS Foundation. https://oeis.org/A022004.
↑ Sloane, N. J. A., ed. "Sequence A005385 (Safe primes)". OEIS Foundation. https://oeis.org/A005385.
↑ Sloane, N. J. A., ed. "Sequence A007703 (Regular primes)". OEIS Foundation. https://oeis.org/A007703.
↑ Sloane, N. J. A., ed. "Sequence A063980 (Pillai primes)". OEIS Foundation. https://oeis.org/A063980.
↑ Sloane, N. J. A., ed. "Sequence A042978 (Stern primes)". OEIS Foundation. https://oeis.org/A042978.
↑ Sloane, N. J. A., ed. "Sequence A104272 (Ramanujan primes)". OEIS Foundation. https://oeis.org/A104272.
↑ Sloane, N. J. A., ed. "Sequence A002387 (Least k such that H(k) > n, where H(k) is the harmonic number sum_{i=1..k} 1/i)". OEIS Foundation. https://oeis.org/A002387.
↑ Sloane, N. J. A., ed. "Sequence A002905 (Number of connected graphs with n edges)". OEIS Foundation. https://oeis.org/A002905.
↑ Sloane, N. J. A., ed. "Sequence A051736 (Number of 3 x n (0,1)-matrices with no consecutive 1's in any row or column)". OEIS Foundation. https://oeis.org/A051736.

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[1] Sloane, N. J. A., ed. "Sequence A022004 (Initial members of prime triples (p, p+2, p+6))". OEIS Foundation. https://oeis.org/A022004.

[2] Sloane, N. J. A., ed. "Sequence A005385 (Safe primes)". OEIS Foundation. https://oeis.org/A005385.

[3] Sloane, N. J. A., ed. "Sequence A007703 (Regular primes)". OEIS Foundation. https://oeis.org/A007703.

[4] Sloane, N. J. A., ed. "Sequence A063980 (Pillai primes)". OEIS Foundation. https://oeis.org/A063980.

[5] Sloane, N. J. A., ed. "Sequence A042978 (Stern primes)". OEIS Foundation. https://oeis.org/A042978.

[6] Sloane, N. J. A., ed. "Sequence A104272 (Ramanujan primes)". OEIS Foundation. https://oeis.org/A104272.

[7] Sloane, N. J. A., ed. "Sequence A002387 (Least k such that H(k) > n, where H(k) is the harmonic number sum_{i=1..k} 1/i)". OEIS Foundation. https://oeis.org/A002387.

[8] Sloane, N. J. A., ed. "Sequence A002905 (Number of connected graphs with n edges)". OEIS Foundation. https://oeis.org/A002905.

[9] Sloane, N. J. A., ed. "Sequence A051736 (Number of 3 x n (0,1)-matrices with no consecutive 1's in any row or column)". OEIS Foundation. https://oeis.org/A051736.

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