18131868 has 18 divisors (see below), whose sum is σ = 45833424. Its totient is φ = 6043944.

The previous prime is 18131857. The next prime is 18131879. The reversal of 18131868 is 86813181.

It is an interprime number because it is at equal distance from previous prime (18131857) and next prime (18131879).

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 503663 = 18131868 / (1 + 8 + 1 + 3 + 1 + 8 + 6 + 8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 251796 + ... + 251867.

Almost surely, 2^18131868 is an apocalyptic number.

18131868 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

18131868 is an abundant number, since it is smaller than the sum of its proper divisors (27701556).

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

18131868 is a wasteful number, since it uses less digits than its factorization.

18131868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503673 (or 503668 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 18131868 is about 4258.1531207790. The cubic root of 18131868 is about 262.7125679557.

The spelling of 18131868 in words is "eighteen million, one hundred thirty-one thousand, eight hundred sixty-eight".