18978564 has 48 divisors (see below), whose sum is σ = 49121856. Its totient is φ = 5654400.

The previous prime is 18978559. The next prime is 18978569. The reversal of 18978564 is 46587981.

It is an interprime number because it is at equal distance from previous prime (18978559) and next prime (18978569).

It is not an unprimeable number, because it can be changed into a prime (18978569) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6874 + ... + 9230.

It is an arithmetic number, because the mean of its divisors is an integer number (1023372).

Almost surely, 2^18978564 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18978564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24560928).

18978564 is an abundant number, since it is smaller than the sum of its proper divisors (30143292).

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

18978564 is a wasteful number, since it uses less digits than its factorization.

18978564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2436 (or 2434 counting only the distinct ones).

The product of its digits is 483840, while the sum is 48.

The square root of 18978564 is about 4356.4393717806. The cubic root of 18978564 is about 266.7397764820.

The spelling of 18978564 in words is "eighteen million, nine hundred seventy-eight thousand, five hundred sixty-four".