18990900 has 54 divisors (see below), whose sum is σ = 59528742. Its totient is φ = 5064000.

The previous prime is 18990883. The next prime is 18990901. The reversal of 18990900 is 909981.

It can be written as a sum of positive squares in 3 ways, for example, as 224676 + 18766224 = 474^2 + 4332^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18990901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 9651 + ... + 11450.

Almost surely, 2^18990900 is an apocalyptic number.

18990900 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18990900 is an abundant number, since it is smaller than the sum of its proper divisors (40537842).

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

18990900 is a wasteful number, since it uses less digits than its factorization.

18990900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21121 (or 21111 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 18990900 is about 4357.8549769353. The cubic root of 18990900 is about 266.7975572710.

The spelling of 18990900 in words is "eighteen million, nine hundred ninety thousand, nine hundred".