69 (number)

 ← 68 69 70 →
Cardinal sixty-nine
Ordinal 69th
(sixty-ninth)
Factorization 3 × 23
Divisors 1, 3, 23, 69
Roman numeral LXIX
Binary 10001012
Ternary 21203
Quaternary 10114
Quinary 2345
Senary 1536
Octal 1058
Duodecimal 5912
Vigesimal 3920
Base 36 1X36

69 (sixty-nine) is a number following 68 and preceding 70.

In mathematics

The aliquot sum of sixty-nine is 27 within the aliquot sequence (69,27,13,1,0) 69 being the third composite number in the 13-aliquot tree.

69 is a semiprime. Furthermore, since the two factors of 69 are both Gaussian primes, 69 is a Blum integer.

Adding up the divisors of 1 through 9 gives 69.

69 is a lucky number.

Because 69 has an odd number of 1s in its binary representation, it is sometimes called an "odious number." Of note is that 69² (4 761) and 69³ (328 509) together use every decimal digit from 0-9. 69 is equal to 105 octal, while 105 is equal to 69 hexadecimal. This same property can be applied to all numbers from 64 to 69.

On many handheld scientific and graphing calculators, the highest factorial that can be calculated, due to memory limitations, is 69! or about 1.711224524×1098.

In other fields

Sixty-nine may also refer to: