18561900 has 72 divisors (see below), whose sum is σ = 61384960. Its totient is φ = 4242240.

The previous prime is 18561869. The next prime is 18561923. The reversal of 18561900 is 916581.

It is a happy number.

It is a super-2 number, since 2×18561900² = 689088263220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2320 + ... + 6519.

Almost surely, 2^18561900 is an apocalyptic number.

18561900 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18561900 is an abundant number, since it is smaller than the sum of its proper divisors (42823060).

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

18561900 is a wasteful number, since it uses less digits than its factorization.

18561900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8863 (or 8856 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 30.

The square root of 18561900 is about 4308.3523532785. The cubic root of 18561900 is about 264.7732723120.

The spelling of 18561900 in words is "eighteen million, five hundred sixty-one thousand, nine hundred".