81320544 has 48 divisors (see below), whose sum is σ = 237187440. Its totient is φ = 27106560.

The previous prime is 81320543. The next prime is 81320549. The reversal of 81320544 is 44502318.

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

It is a super-2 number, since 2×81320544² = 13226061752911872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81320543) 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, 46197 + ... + 47924.

It is an arithmetic number, because the mean of its divisors is an integer number (4941405).

Almost surely, 2^81320544 is an apocalyptic number.

It is an amenable number.

81320544 is an abundant number, since it is smaller than the sum of its proper divisors (155866896).

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

81320544 is a wasteful number, since it uses less digits than its factorization.

81320544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94140 (or 94126 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 81320544 is about 9017.7904167263. The cubic root of 81320544 is about 433.2448660953.

The spelling of 81320544 in words is "eighty-one million, three hundred twenty thousand, five hundred forty-four".