81533880 has 48 divisors (see below), whose sum is σ = 264986280. Its totient is φ = 21742272.

The previous prime is 81533867. The next prime is 81533911. The reversal of 81533880 is 8833518.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 112882 + ... + 113601.

Almost surely, 2^81533880 is an apocalyptic number.

It is an amenable number.

81533880 is an abundant number, since it is smaller than the sum of its proper divisors (183452400).

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

81533880 is a wasteful number, since it uses less digits than its factorization.

81533880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226500 (or 226493 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 81533880 is about 9029.6112873146. The cubic root of 81533880 is about 433.6233929137.

The spelling of 81533880 in words is "eighty-one million, five hundred thirty-three thousand, eight hundred eighty".