18566450721 has 48 divisors (see below), whose sum is σ = 34229546624. Its totient is φ = 9793281024.

The previous prime is 18566450713. The next prime is 18566450753. The reversal of 18566450721 is 12705466581.

18566450721 is a `hidden beast` number, since 1 + 85 + 6 + 64 + 507 + 2 + 1 = 666.

It is not a de Polignac number, because 18566450721 - 2³ = 18566450713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18566450321) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 397696 + ... + 441921.

Almost surely, 2^18566450721 is an apocalyptic number.

It is an amenable number.

18566450721 is a deficient number, since it is larger than the sum of its proper divisors (15663095903).

18566450721 is an equidigital number, since it uses as much as digits as its factorization.

18566450721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 839652 (or 839640 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 18566450721 in words is "eighteen billion, five hundred sixty-six million, four hundred fifty thousand, seven hundred twenty-one".