81320135860 has 48 divisors (see below), whose sum is σ = 173989810512. Its totient is φ = 31920896000.

The previous prime is 81320135839. The next prime is 81320135873. The reversal of 81320135860 is 6853102318.

It can be written as a sum of positive squares in 8 ways, for example, as 7438372516 + 73881763344 = 86246^2 + 271812^2 .

It is a super-2 number, since 2×81320135860² (a number of 23 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50130 + ... + 406390.

It is an arithmetic number, because the mean of its divisors is an integer number (3624787719).

Almost surely, 2^81320135860 is an apocalyptic number.

It is an amenable number.

81320135860 is an abundant number, since it is smaller than the sum of its proper divisors (92669674652).

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

81320135860 is a wasteful number, since it uses less digits than its factorization.

81320135860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356484 (or 356482 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 37.

The spelling of 81320135860 in words is "eighty-one billion, three hundred twenty million, one hundred thirty-five thousand, eight hundred sixty".