18021988 has 12 divisors (see below), whose sum is σ = 32272240. Its totient is φ = 8801352.

The previous prime is 18021977. The next prime is 18022007. The reversal of 18021988 is 88912081.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52218 + ... + 52561.

Almost surely, 2^18021988 is an apocalyptic number.

It is an amenable number.

18021988 is a deficient number, since it is larger than the sum of its proper divisors (14250252).

18021988 is a wasteful number, since it uses less digits than its factorization.

18021988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104826 (or 104824 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 18021988 is about 4245.2312068956. The cubic root of 18021988 is about 262.1808087055.

The spelling of 18021988 in words is "eighteen million, twenty-one thousand, nine hundred eighty-eight".