81320831 has 4 divisors (see below), whose sum is σ = 81339912. Its totient is φ = 81301752.

The previous prime is 81320807. The next prime is 81320873. The reversal of 81320831 is 13802318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81320831 is a prime.

It is a super-2 number, since 2×81320831² = 13226155109061122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81320831.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81320891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101 + ... + 12753.

It is an arithmetic number, because the mean of its divisors is an integer number (20334978).

Almost surely, 2^81320831 is an apocalyptic number.

81320831 is a deficient number, since it is larger than the sum of its proper divisors (19081).

81320831 is a wasteful number, since it uses less digits than its factorization.

81320831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19080.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 81320831 is about 9017.8063297013. The cubic root of 81320831 is about 433.2453757703.

The spelling of 81320831 in words is "eighty-one million, three hundred twenty thousand, eight hundred thirty-one".