16561978024 has 16 divisors (see below), whose sum is σ = 31068865620. Its totient is φ = 8276947200.

The previous prime is 16561977973. The next prime is 16561978033. The reversal of 16561978024 is 42087916561.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 14912805924 + 1649172100 = 122118^2 + 40610^2 .

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, 487777 + ... + 520624.

Almost surely, 2^16561978024 is an apocalyptic number.

It is an amenable number.

16561978024 is a deficient number, since it is larger than the sum of its proper divisors (14506887596).

16561978024 is a wasteful number, since it uses less digits than its factorization.

16561978024 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010460 (or 1010456 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 16561978024 in words is "sixteen billion, five hundred sixty-one million, nine hundred seventy-eight thousand, twenty-four".