18972978 has 16 divisors (see below), whose sum is σ = 38028000. Its totient is φ = 6310656.

The previous prime is 18972977. The next prime is 18972991. The reversal of 18972978 is 87927981.

It is a self number, because there is not a number n which added to its sum of digits gives 18972978.

It is not an unprimeable number, because it can be changed into a prime (18972973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175 + ... + 6162.

It is an arithmetic number, because the mean of its divisors is an integer number (2376750).

Almost surely, 2^18972978 is an apocalyptic number.

18972978 is an abundant number, since it is smaller than the sum of its proper divisors (19055022).

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

18972978 is a wasteful number, since it uses less digits than its factorization.

18972978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6841.

The product of its digits is 508032, while the sum is 51.

The square root of 18972978 is about 4355.7982046922. The cubic root of 18972978 is about 266.7136038907.

The spelling of 18972978 in words is "eighteen million, nine hundred seventy-two thousand, nine hundred seventy-eight".