81920928 has 48 divisors (see below), whose sum is σ = 215732160. Its totient is φ = 27219456.

The previous prime is 81920899. The next prime is 81920929. The reversal of 81920928 is 82902918.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×81920928² = 13422076888762368, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81920929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33276 + ... + 35652.

It is an arithmetic number, because the mean of its divisors is an integer number (4494420).

Almost surely, 2^81920928 is an apocalyptic number.

It is an amenable number.

81920928 is an abundant number, since it is smaller than the sum of its proper divisors (133811232).

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

81920928 is a wasteful number, since it uses less digits than its factorization.

81920928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2749 (or 2741 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 81920928 is about 9051.0180642843. The cubic root of 81920928 is about 434.3084586096.

The spelling of 81920928 in words is "eighty-one million, nine hundred twenty thousand, nine hundred twenty-eight".