81813581928 has 64 divisors (see below), whose sum is σ = 244741492800. Its totient is φ = 25173408960.

The previous prime is 81813581891. The next prime is 81813581939. The reversal of 81813581928 is 82918531818.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14565138 + ... + 14570753.

It is an arithmetic number, because the mean of its divisors is an integer number (3824085825).

Almost surely, 2^81813581928 is an apocalyptic number.

It is an amenable number.

81813581928 is an abundant number, since it is smaller than the sum of its proper divisors (162927910872).

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

81813581928 is a wasteful number, since it uses less digits than its factorization.

81813581928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29135919 (or 29135909 counting only the distinct ones).

The product of its digits is 1105920, while the sum is 54.

The spelling of 81813581928 in words is "eighty-one billion, eight hundred thirteen million, five hundred eighty-one thousand, nine hundred twenty-eight".