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# 227 (number)

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 Title: 227 (number) Author: World Heritage Encyclopedia Language: English Subject: Collection: Integers Publisher: World Heritage Encyclopedia Publication Date:

### 227 (number)

 ← 226 227 228 →
Cardinal two hundred twenty-seven
Ordinal 227th
(two hundred and twenty-seventh)
Factorization 227
Prime yes
Roman numeral CCXXVII
Binary 111000112
Ternary 221023
Quaternary 32034
Quinary 14025
Senary 10156
Octal 3438
Duodecimal 16B12
Hexadecimal E316
Vigesimal B720
Base 36 6B36

227 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]

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's A022004 ", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
2. ^ "Sloane's A005385 ", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
3. ^ "Sloane's A007703 : Regular primes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
4. ^ "Sloane's A063980 : Pillai primes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
5. ^ "Sloane's A042978 ", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
6. ^ "Sloane's A104272 : Ramanujan primes", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
7. ^ "Sloane's A002387 : Least k such that H(k) > n, where H(k) is the harmonic number sum_{i=1..k} 1/i", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
8. ^ "Sloane's A002905 ", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
9. ^ "Sloane's A051736 ", The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
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