81330920 has 32 divisors (see below), whose sum is σ = 199631520. Its totient is φ = 29574720.

The previous prime is 81330863. The next prime is 81330923. The reversal of 81330920 is 2903318.

It is a super-2 number, since 2×81330920² = 13229437096092800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81330920.

It is not an unprimeable number, because it can be changed into a prime (81330923) 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 7 ways as a sum of consecutive naturals, for example, 91982 + ... + 92861.

It is an arithmetic number, because the mean of its divisors is an integer number (6238485).

Almost surely, 2^81330920 is an apocalyptic number.

It is an amenable number.

81330920 is an abundant number, since it is smaller than the sum of its proper divisors (118300600).

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

81330920 is a wasteful number, since it uses less digits than its factorization.

81330920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184865 (or 184861 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 81330920 is about 9018.3657056032. The cubic root of 81330920 is about 433.2632917696.

The spelling of 81330920 in words is "eighty-one million, three hundred thirty thousand, nine hundred twenty".