81813504 has 56 divisors (see below), whose sum is σ = 218221560. Its totient is φ = 27262976.

The previous prime is 81813439. The next prime is 81813551. The reversal of 81813504 is 40531818.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22912 + ... + 26240.

Almost surely, 2^81813504 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 81813504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109110780).

81813504 is an abundant number, since it is smaller than the sum of its proper divisors (136408056).

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

81813504 is an equidigital number, since it uses as much as digits as its factorization.

81813504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3358 (or 3334 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 81813504 is about 9045.0817575078. The cubic root of 81813504 is about 434.1185374216.

The spelling of 81813504 in words is "eighty-one million, eight hundred thirteen thousand, five hundred four".