18978972 has 12 divisors (see below), whose sum is σ = 44284296. Its totient is φ = 6326320.

The previous prime is 18978959. The next prime is 18978989. The reversal of 18978972 is 27987981.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 790779 + ... + 790802.

It is an arithmetic number, because the mean of its divisors is an integer number (3690358).

Almost surely, 2^18978972 is an apocalyptic number.

18978972 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18978972 is an abundant number, since it is smaller than the sum of its proper divisors (25305324).

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

18978972 is a wasteful number, since it uses less digits than its factorization.

18978972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1581588 (or 1581586 counting only the distinct ones).

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

The square root of 18978972 is about 4356.4861987616. The cubic root of 18978972 is about 266.7416879201.

Subtracting 18978972 from its reverse (27987981), we obtain a palindrome (9009009).

The spelling of 18978972 in words is "eighteen million, nine hundred seventy-eight thousand, nine hundred seventy-two".