81320384 has 56 divisors (see below), whose sum is σ = 175125888. Its totient is φ = 37314560.

The previous prime is 81320377. The next prime is 81320417. The reversal of 81320384 is 48302318.

It is a happy number.

It is a super-2 number, since 2×81320384² = 13226009707814912, which contains 22 as substring.

It is a hoax number, since the sum of its digits (29) 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 7 ways as a sum of consecutive naturals, for example, 43697 + ... + 45519.

It is an arithmetic number, because the mean of its divisors is an integer number (3127248).

Almost surely, 2^81320384 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 81320384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87562944).

81320384 is an abundant number, since it is smaller than the sum of its proper divisors (93805504).

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

81320384 is a wasteful number, since it uses less digits than its factorization.

81320384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1893 (or 1883 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 81320384 is about 9017.7815453691. The cubic root of 81320384 is about 433.2445819555.

The spelling of 81320384 in words is "eighty-one million, three hundred twenty thousand, three hundred eighty-four".