81359728 has 20 divisors (see below), whose sum is σ = 158583600. Its totient is φ = 40434944.

The previous prime is 81359711. The next prime is 81359731. The reversal of 81359728 is 82795318.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12553 + ... + 17896.

It is an arithmetic number, because the mean of its divisors is an integer number (7929180).

Almost surely, 2^81359728 is an apocalyptic number.

It is an amenable number.

81359728 is a deficient number, since it is larger than the sum of its proper divisors (77223872).

81359728 is a wasteful number, since it uses less digits than its factorization.

81359728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30624 (or 30618 counting only the distinct ones).

The product of its digits is 120960, while the sum is 43.

The square root of 81359728 is about 9019.9627493688. The cubic root of 81359728 is about 433.3144407279.

The spelling of 81359728 in words is "eighty-one million, three hundred fifty-nine thousand, seven hundred twenty-eight".