81819264 has 64 divisors (see below), whose sum is σ = 220466880. Its totient is φ = 26880000.

The previous prime is 81819229. The next prime is 81819281. The reversal of 81819264 is 46291818.

It is a tau number, because it is divible by the number of its divisors (64).

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, 25764 + ... + 28764.

It is an arithmetic number, because the mean of its divisors is an integer number (3444795).

Almost surely, 2^81819264 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 81819264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110233440).

81819264 is an abundant number, since it is smaller than the sum of its proper divisors (138647616).

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

81819264 is a wasteful number, since it uses less digits than its factorization.

81819264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3089 (or 3077 counting only the distinct ones).

The product of its digits is 27648, while the sum is 39.

The square root of 81819264 is about 9045.4001569859. The cubic root of 81819264 is about 434.1287250801.

The spelling of 81819264 in words is "eighty-one million, eight hundred nineteen thousand, two hundred sixty-four".