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65 (number)

← 64 65 66 →
Cardinal sixty-five
Ordinal 65th
(sixty-fifth)
Factorization 5 × 13
Divisors 1, 5, 13, 65
Roman numeral LXV
Binary 10000012
Ternary 21023
Quaternary 10014
Quinary 2305
Senary 1456
Octal 1018
Duodecimal 5512
Hexadecimal 4116
Vigesimal 3520
Base 36 1T36

65 (sixty-five) is the natural number following 64 and preceding 66.

Sixty-five is the 23rdsemiprime and the 3rd of the form (5.q). It is an octagonal number. It is also a Cullen number. Given 65, the Mertens function returns 0.

Sixty-five has an aliquot sum of 19 and is the first composite number in the 19-aliquot tree.

This number is the magic constant of 5 by 5 normal magic square:


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