18978864 has 40 divisors (see below), whose sum is σ = 51163392. Its totient is φ = 6050880.

The previous prime is 18978857. The next prime is 18978871. The reversal of 18978864 is 46887981.

It is an interprime number because it is at equal distance from previous prime (18978857) and next prime (18978871).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7492 + ... + 9699.

Almost surely, 2^18978864 is an apocalyptic number.

It is an amenable number.

18978864 is an abundant number, since it is smaller than the sum of its proper divisors (32184528).

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

18978864 is a wasteful number, since it uses less digits than its factorization.

18978864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17225 (or 17219 counting only the distinct ones).

The product of its digits is 774144, while the sum is 51.

The square root of 18978864 is about 4356.4738034332. The cubic root of 18978864 is about 266.7411819539.

The spelling of 18978864 in words is "eighteen million, nine hundred seventy-eight thousand, eight hundred sixty-four".