81320436 has 36 divisors (see below), whose sum is σ = 213175872. Its totient is φ = 27106488.

The previous prime is 81320429. The next prime is 81320441. The reversal of 81320436 is 63402318.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×81320436² = 13226026622460192, 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 an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40860 + ... + 42803.

It is an arithmetic number, because the mean of its divisors is an integer number (5921552).

Almost surely, 2^81320436 is an apocalyptic number.

It is an amenable number.

81320436 is an abundant number, since it is smaller than the sum of its proper divisors (131855436).

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

81320436 is a wasteful number, since it uses less digits than its factorization.

81320436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83682 (or 83668 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 81320436 is about 9017.7844285612. The cubic root of 81320436 is about 433.2446743010.

The spelling of 81320436 in words is "eighty-one million, three hundred twenty thousand, four hundred thirty-six".