81563632164 has 72 divisors (see below), whose sum is σ = 239491074368. Its totient is φ = 22921859520.

The previous prime is 81563632147. The next prime is 81563632201. The reversal of 81563632164 is 46123636518.

81563632164 is a `hidden beast` number, since 8 + 1 + 5 + 6 + 3 + 632 + 1 + 6 + 4 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2637622 + ... + 2668365.

Almost surely, 2^81563632164 is an apocalyptic number.

81563632164 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81563632164 is an abundant number, since it is smaller than the sum of its proper divisors (157927442204).

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

81563632164 is a wasteful number, since it uses less digits than its factorization.

81563632164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5306065 (or 5306060 counting only the distinct ones).

The product of its digits is 622080, while the sum is 45.

The spelling of 81563632164 in words is "eighty-one billion, five hundred sixty-three million, six hundred thirty-two thousand, one hundred sixty-four".