18664642521 has 12 divisors (see below), whose sum is σ = 30811473472. Its totient is φ = 10665509976.

The previous prime is 18664642517. The next prime is 18664642547. The reversal of 18664642521 is 12524646681.

It is a happy number.

18664642521 is a `hidden beast` number, since 1 + 8 + 6 + 64 + 64 + 2 + 521 = 666.

It is not a de Polignac number, because 18664642521 - 2² = 18664642517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18664632521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 148132021 + ... + 148132146.

Almost surely, 2^18664642521 is an apocalyptic number.

It is an amenable number.

18664642521 is a deficient number, since it is larger than the sum of its proper divisors (12146830951).

18664642521 is a wasteful number, since it uses less digits than its factorization.

18664642521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296264180 (or 296264177 counting only the distinct ones).

The product of its digits is 552960, while the sum is 45.

The spelling of 18664642521 in words is "eighteen billion, six hundred sixty-four million, six hundred forty-two thousand, five hundred twenty-one".