81320512 has 56 divisors (see below), whose sum is σ = 198623936. Its totient is φ = 32168448.

The previous prime is 81320501. The next prime is 81320527. The reversal of 81320512 is 21502318.

It is a tau number, because it is divible by the number of its divisors (56).

It is a super-2 number, since 2×81320512² = 13226051343884288, which contains 22 as substring.

It is an unprimeable number.

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, 1158 + ... + 12805.

It is an arithmetic number, because the mean of its divisors is an integer number (3546856).

Almost surely, 2^81320512 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 81320512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99311968).

81320512 is an abundant number, since it is smaller than the sum of its proper divisors (117303424).

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

81320512 is a wasteful number, since it uses less digits than its factorization.

81320512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13995 (or 13985 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 81320512 is about 9017.7886424555. The cubic root of 81320512 is about 433.2448092674.

The spelling of 81320512 in words is "eighty-one million, three hundred twenty thousand, five hundred twelve".