81655872 has 28 divisors (see below), whose sum is σ = 216048336. Its totient is φ = 27218560.

The previous prime is 81655859. The next prime is 81655883. The reversal of 81655872 is 27855618.

It is a super-3 number, since 3×81655872³ (a number of 25 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 212454 + ... + 212837.

It is an arithmetic number, because the mean of its divisors is an integer number (7716012).

Almost surely, 2^81655872 is an apocalyptic number.

It is an amenable number.

81655872 is an abundant number, since it is smaller than the sum of its proper divisors (134392464).

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

81655872 is a wasteful number, since it uses less digits than its factorization.

81655872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425306 (or 425296 counting only the distinct ones).

The product of its digits is 134400, while the sum is 42.

The square root of 81655872 is about 9036.3638704957. The cubic root of 81655872 is about 433.8395493727.

The spelling of 81655872 in words is "eighty-one million, six hundred fifty-five thousand, eight hundred seventy-two".