281 (number)

Short description: Natural number

| <- 280  | 281 |  282 ->

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← 200 210 220 230 240 250 260 270 280 290 →

List of numbers — Integers

← 0 100 200 300 400 500 600 700 800 900 →

Cardinal| two hundred eighty-one
Ordinal| 281st
(two hundred eighty-first)
Factorization| prime
Prime| 60th
Greek numeral| ΣΠΑ´
Roman numeral| CCLXXXI
Binary| 1000110012
Ternary| 1011023
Quaternary| 101214
Quinary| 21115
Senary| 11456
Octal| 4318
Duodecimal| 1B512
Hexadecimal| 11916
Vigesimal| E120
Base 36| 7T36

281 is the 60th prime, twin prime with 283, Sophie Germain prime, sum of the first fourteen primes, sum of seven consecutive primes (29 + 31 + 37 + 41 + 43 + 47 + 53), Chen prime, Eisenstein prime with no imaginary part, centered decagonal number.

281 is the smallest prime p such that the decimal period length of the reciprocal of p is (p−1)/10, i.e. the period length of 1/281 is 28. However, in binary, it has period length 70.

The generalized repunit number 281p−1280 is composite for all prime p < 60000\.

NANP telephone area code 281 is an overlay code serving Houston, Texas, and its environs.

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