81955433664 has 112 divisors (see below), whose sum is σ = 259467238240. Its totient is φ = 25217049600.

The previous prime is 81955433633. The next prime is 81955433669. The reversal of 81955433664 is 46633455918.

81955433664 is a `hidden beast` number, since 8 + 1 + 9 + 5 + 543 + 36 + 64 = 666.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81955433664.

It is not an unprimeable number, because it can be changed into a prime (81955433669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1801687 + ... + 1846614.

It is an arithmetic number, because the mean of its divisors is an integer number (2316671770).

Almost surely, 2^81955433664 is an apocalyptic number.

It is an amenable number.

81955433664 is an abundant number, since it is smaller than the sum of its proper divisors (177511804576).

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

81955433664 is a wasteful number, since it uses less digits than its factorization.

81955433664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3648335 (or 3648319 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 54.

The spelling of 81955433664 in words is "eighty-one billion, nine hundred fifty-five million, four hundred thirty-three thousand, six hundred sixty-four".