18381972 has 24 divisors (see below), whose sum is σ = 49018816. Its totient is φ = 5251968.

The previous prime is 18381967. The next prime is 18381973. The reversal of 18381972 is 27918381.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 18381972.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18381973) 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 7 ways as a sum of consecutive naturals, for example, 109333 + ... + 109500.

Almost surely, 2^18381972 is an apocalyptic number.

18381972 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18381972 is an abundant number, since it is smaller than the sum of its proper divisors (30636844).

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

18381972 is a wasteful number, since it uses less digits than its factorization.

18381972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218847 (or 218845 counting only the distinct ones).

The product of its digits is 24192, while the sum is 39.

The square root of 18381972 is about 4287.4202033391. The cubic root of 18381972 is about 263.9149749150.

The spelling of 18381972 in words is "eighteen million, three hundred eighty-one thousand, nine hundred seventy-two".