18381988 has 12 divisors (see below), whose sum is σ = 32206720. Its totient is φ = 9180072.

The previous prime is 18381973. The next prime is 18381989. The reversal of 18381988 is 88918381.

It is not an unprimeable number, because it can be changed into a prime (18381989) 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 3 ways as a sum of consecutive naturals, for example, 1945 + ... + 6367.

Almost surely, 2^18381988 is an apocalyptic number.

It is an amenable number.

18381988 is a deficient number, since it is larger than the sum of its proper divisors (13824732).

18381988 is a wasteful number, since it uses less digits than its factorization.

18381988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5466 (or 5464 counting only the distinct ones).

The product of its digits is 110592, while the sum is 46.

The square root of 18381988 is about 4287.4220692626. The cubic root of 18381988 is about 263.9150514871.

The spelling of 18381988 in words is "eighteen million, three hundred eighty-one thousand, nine hundred eighty-eight".