81757065 has 32 divisors (see below), whose sum is σ = 147006720. Its totient is φ = 38497536.

The previous prime is 81757033. The next prime is 81757069. The reversal of 81757065 is 56075718.

It is not a de Polignac number, because 81757065 - 2⁵ = 81757033 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (81757069) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4630 + ... + 13599.

It is an arithmetic number, because the mean of its divisors is an integer number (4593960).

Almost surely, 2^81757065 is an apocalyptic number.

It is an amenable number.

81757065 is a deficient number, since it is larger than the sum of its proper divisors (65249655).

81757065 is a wasteful number, since it uses less digits than its factorization.

81757065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18273.

The product of its (nonzero) digits is 58800, while the sum is 39.

The square root of 81757065 is about 9041.9613469645. The cubic root of 81757065 is about 434.0186889812.

The spelling of 81757065 in words is "eighty-one million, seven hundred fifty-seven thousand, sixty-five".