81564508804 has 12 divisors (see below), whose sum is σ = 142884898128. Its totient is φ = 40740252200.

The previous prime is 81564508741. The next prime is 81564508819. The reversal of 81564508804 is 40880546518.

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, 10496182 + ... + 10503949.

It is an arithmetic number, because the mean of its divisors is an integer number (11907074844).

Almost surely, 2^81564508804 is an apocalyptic number.

It is an amenable number.

81564508804 is a deficient number, since it is larger than the sum of its proper divisors (61320389324).

81564508804 is a wasteful number, since it uses less digits than its factorization.

81564508804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21001106 (or 21001104 counting only the distinct ones).

The product of its (nonzero) digits is 1228800, while the sum is 49.

The spelling of 81564508804 in words is "eighty-one billion, five hundred sixty-four million, five hundred eight thousand, eight hundred four".