81302564 has 18 divisors (see below), whose sum is σ = 165509190. Its totient is φ = 34843872.

The previous prime is 81302521. The next prime is 81302581. The reversal of 81302564 is 46520318.

It can be written as a sum of positive squares in only one way, i.e., 58644964 + 22657600 = 7658^2 + 4760^2 .

It is a super-2 number, since 2×81302564² = 13220213825948192, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 207209 + ... + 207600.

It is an arithmetic number, because the mean of its divisors is an integer number (9194955).

Almost surely, 2^81302564 is an apocalyptic number.

It is an amenable number.

81302564 is an abundant number, since it is smaller than the sum of its proper divisors (84206626).

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

81302564 is a wasteful number, since it uses less digits than its factorization.

81302564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414827 (or 414818 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 81302564 is about 9016.7934433478. The cubic root of 81302564 is about 433.2129335459.

The spelling of 81302564 in words is "eighty-one million, three hundred two thousand, five hundred sixty-four".