18978690 has 16 divisors (see below), whose sum is σ = 45548928. Its totient is φ = 5060976.

The previous prime is 18978683. The next prime is 18978691. The reversal of 18978690 is 9687981.

It is a happy number.

It is a super-2 number, since 2×18978690² = 720381348232200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18978691) 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, 316282 + ... + 316341.

It is an arithmetic number, because the mean of its divisors is an integer number (2846808).

Almost surely, 2^18978690 is an apocalyptic number.

18978690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18978690 is an abundant number, since it is smaller than the sum of its proper divisors (26570238).

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

18978690 is a wasteful number, since it uses less digits than its factorization.

18978690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632633.

The product of its (nonzero) digits is 217728, while the sum is 48.

The square root of 18978690 is about 4356.4538331078. The cubic root of 18978690 is about 266.7403667820.

The spelling of 18978690 in words is "eighteen million, nine hundred seventy-eight thousand, six hundred ninety".