18978840 has 64 divisors (see below), whose sum is σ = 63266400. Its totient is φ = 5060736.

The previous prime is 18978811. The next prime is 18978857. The reversal of 18978840 is 4887981.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7707 + ... + 9866.

Almost surely, 2^18978840 is an apocalyptic number.

18978840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18978840 is an abundant number, since it is smaller than the sum of its proper divisors (44287560).

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

18978840 is a wasteful number, since it uses less digits than its factorization.

18978840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17593 (or 17583 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 18978840 is about 4356.4710489110. The cubic root of 18978840 is about 266.7410695167.

The spelling of 18978840 in words is "eighteen million, nine hundred seventy-eight thousand, eight hundred forty".