18979920 has 200 divisors, whose sum is σ = 68868360. Its totient is φ = 4838400.

The previous prime is 18979901. The next prime is 18979931. The reversal of 18979920 is 2997981.

It can be written as a sum of positive squares in 4 ways, for example, as 6533136 + 12446784 = 2556^2 + 3528^2 .

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 39 ways as a sum of consecutive naturals, for example, 187870 + ... + 187970.

Almost surely, 2^18979920 is an apocalyptic number.

18979920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18979920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34434180).

18979920 is an abundant number, since it is smaller than the sum of its proper divisors (49888440).

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

18979920 is a wasteful number, since it uses less digits than its factorization.

18979920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 18979920 is about 4356.5950006857. The cubic root of 18979920 is about 266.7461290969.

The spelling of 18979920 in words is "eighteen million, nine hundred seventy-nine thousand, nine hundred twenty".