81757044 has 36 divisors (see below), whose sum is σ = 213333120. Its totient is φ = 26372880.

The previous prime is 81757033. The next prime is 81757069. The reversal of 81757044 is 44075718.

81757044 is a `hidden beast` number, since 81 + 7 + 570 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35514 + ... + 37745.

It is an arithmetic number, because the mean of its divisors is an integer number (5925920).

Almost surely, 2^81757044 is an apocalyptic number.

It is an amenable number.

81757044 is an abundant number, since it is smaller than the sum of its proper divisors (131576076).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81757044 is a wasteful number, since it uses less digits than its factorization.

81757044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73300 (or 73295 counting only the distinct ones).

The product of its (nonzero) digits is 31360, while the sum is 36.

The square root of 81757044 is about 9041.9601857119. The cubic root of 81757044 is about 434.0186518207.

The spelling of 81757044 in words is "eighty-one million, seven hundred fifty-seven thousand, forty-four".