81857560 has 32 divisors (see below), whose sum is σ = 184991040. Its totient is φ = 32598784.

The previous prime is 81857551. The next prime is 81857563. The reversal of 81857560 is 6575818.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81857563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4929 + ... + 13711.

It is an arithmetic number, because the mean of its divisors is an integer number (5780970).

Almost surely, 2^81857560 is an apocalyptic number.

It is an amenable number.

81857560 is an abundant number, since it is smaller than the sum of its proper divisors (103133480).

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

81857560 is a wasteful number, since it uses less digits than its factorization.

81857560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9027 (or 9023 counting only the distinct ones).

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 81857560 is about 9047.5167863895. The cubic root of 81857560 is about 434.1964467047.

The spelling of 81857560 in words is "eighty-one million, eight hundred fifty-seven thousand, five hundred sixty".