81915860 has 96 divisors (see below), whose sum is σ = 201180672. Its totient is φ = 27740160.

The previous prime is 81915833. The next prime is 81915871. The reversal of 81915860 is 6851918.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 189845 + ... + 190275.

It is an arithmetic number, because the mean of its divisors is an integer number (2095632).

Almost surely, 2^81915860 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 81915860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100590336).

81915860 is an abundant number, since it is smaller than the sum of its proper divisors (119264812).

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

81915860 is a wasteful number, since it uses less digits than its factorization.

81915860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 513 (or 511 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 38.

The square root of 81915860 is about 9050.7380914487. The cubic root of 81915860 is about 434.2995023282.

The spelling of 81915860 in words is "eighty-one million, nine hundred fifteen thousand, eight hundred sixty".