18315990 has 128 divisors (see below), whose sum is σ = 60963840. Its totient is φ = 3801600.

The previous prime is 18315989. The next prime is 18316003. The reversal of 18315990 is 9951381.

It is a happy number.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 20350 + ... + 21230.

It is an arithmetic number, because the mean of its divisors is an integer number (476280).

Almost surely, 2^18315990 is an apocalyptic number.

18315990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18315990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30481920).

18315990 is an abundant number, since it is smaller than the sum of its proper divisors (42647850).

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

18315990 is a wasteful number, since it uses less digits than its factorization.

18315990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 915 (or 909 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 18315990 is about 4279.7184486833. The cubic root of 18315990 is about 263.5988224929.

The spelling of 18315990 in words is "eighteen million, three hundred fifteen thousand, nine hundred ninety".