18231988 has 6 divisors (see below), whose sum is σ = 31905986. Its totient is φ = 9115992.

The previous prime is 18231977. The next prime is 18231989. The reversal of 18231988 is 88913281.

It can be written as a sum of positive squares in only one way, i.e., 16305444 + 1926544 = 4038^2 + 1388^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18231988.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18231989) 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 as a sum of consecutive naturals, namely, 2278995 + ... + 2279002.

Almost surely, 2^18231988 is an apocalyptic number.

It is an amenable number.

18231988 is a deficient number, since it is larger than the sum of its proper divisors (13673998).

18231988 is a wasteful number, since it uses less digits than its factorization.

18231988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4558001 (or 4557999 counting only the distinct ones).

The product of its digits is 27648, while the sum is 40.

The square root of 18231988 is about 4269.8932070955. The cubic root of 18231988 is about 263.1952267683.

The spelling of 18231988 in words is "eighteen million, two hundred thirty-one thousand, nine hundred eighty-eight".