18401988 has 24 divisors (see below), whose sum is σ = 46841760. Its totient is φ = 5576320.

The previous prime is 18401983. The next prime is 18402011. The reversal of 18401988 is 88910481.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (18401983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69573 + ... + 69836.

It is an arithmetic number, because the mean of its divisors is an integer number (1951740).

Almost surely, 2^18401988 is an apocalyptic number.

It is an amenable number.

18401988 is an abundant number, since it is smaller than the sum of its proper divisors (28439772).

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

18401988 is a wasteful number, since it uses less digits than its factorization.

18401988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139427 (or 139425 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 39.

The square root of 18401988 is about 4289.7538390915. The cubic root of 18401988 is about 264.0107318870.

It can be divided in two parts, 1840 and 1988, that added together give a triangular number (3828 = T₈₇).

The spelling of 18401988 in words is "eighteen million, four hundred one thousand, nine hundred eighty-eight".