81908928 has 112 divisors (see below), whose sum is σ = 243596160. Its totient is φ = 26986752.

The previous prime is 81908923. The next prime is 81908951. The reversal of 81908928 is 82980918.

It is a super-2 number, since 2×81908928² = 13418144972218368, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81908923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 184675 + ... + 185117.

Almost surely, 2^81908928 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81908928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121798080).

81908928 is an abundant number, since it is smaller than the sum of its proper divisors (161687232).

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

81908928 is a wasteful number, since it uses less digits than its factorization.

81908928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 571 (or 555 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 81908928 is about 9050.3551311537. The cubic root of 81908928 is about 434.2872513466.

The spelling of 81908928 in words is "eighty-one million, nine hundred eight thousand, nine hundred twenty-eight".