# 511 (number)

 ← 510 511 512 →
Cardinalfive hundred eleven
Ordinal511th
(five hundred eleventh)
Factorization7 × 73
Greek numeralΦΙΑ´
Roman numeralDXI
Binary1111111112
Ternary2002213
Octal7778
Duodecimal36712

511 is the natural number following 510 and preceding 512.

It is a Mersenne number, being one less than a power of 2: ${\displaystyle 511=2^{9}-1}$. As a result, 511 is a palindromic number and a repdigit in bases 2 (1111111112). It is also palindromic and a repdigit in base 8 (7778).

It is a generalized heptagonal number (sequence A085787 in the OEIS), since ${\displaystyle 511={\frac {1}{2}}(5n^{2}-3n)}$ when ${\displaystyle n=-14}$.

It is a Harshad number in bases 3, 5, 7, 10, 13 and 15.

## Special use in computers

The octal representation of 511 (7778) is commonly used by Unix commands to specify a custom record separator in order to "slurp" input as a whole, rather than line-by-line (i.e. separated at newline characters).