18311988 has 12 divisors (see below), whose sum is σ = 42728000. Its totient is φ = 6103992.

The previous prime is 18311987. The next prime is 18312013. The reversal of 18311988 is 88911381.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18311983) by changing a digit.

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, 762988 + ... + 763011.

Almost surely, 2^18311988 is an apocalyptic number.

It is an amenable number.

18311988 is an abundant number, since it is smaller than the sum of its proper divisors (24416012).

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

18311988 is a wasteful number, since it uses less digits than its factorization.

18311988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1526006 (or 1526004 counting only the distinct ones).

The product of its digits is 13824, while the sum is 39.

The square root of 18311988 is about 4279.2508690190. The cubic root of 18311988 is about 263.5796225238.

The spelling of 18311988 in words is "eighteen million, three hundred eleven thousand, nine hundred eighty-eight".