81125824 has 56 divisors (see below), whose sum is σ = 174485808. Its totient is φ = 37201920.

The previous prime is 81125809. The next prime is 81125831. The reversal of 81125824 is 42852118.

It is a hoax number, since the sum of its digits (31) 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, 233619 + ... + 233965.

It is an arithmetic number, because the mean of its divisors is an integer number (3115818).

Almost surely, 2^81125824 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 81125824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87242904).

81125824 is an abundant number, since it is smaller than the sum of its proper divisors (93359984).

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

81125824 is a wasteful number, since it uses less digits than its factorization.

81125824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653 (or 643 counting only the distinct ones).

The product of its digits is 5120, while the sum is 31.

The square root of 81125824 is about 9006.9875097060. The cubic root of 81125824 is about 432.8987917429.

The spelling of 81125824 in words is "eighty-one million, one hundred twenty-five thousand, eight hundred twenty-four".