18115820 has 24 divisors (see below), whose sum is σ = 38283504. Its totient is φ = 7200576.

The previous prime is 18115813. The next prime is 18115831. The reversal of 18115820 is 2851181.

It is a self number, because there is not a number n which added to its sum of digits gives 18115820.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 482 + ... + 6038.

It is an arithmetic number, because the mean of its divisors is an integer number (1595146).

Almost surely, 2^18115820 is an apocalyptic number.

18115820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18115820 is an abundant number, since it is smaller than the sum of its proper divisors (20167684).

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

18115820 is a wasteful number, since it uses less digits than its factorization.

18115820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5729 (or 5727 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 26.

The square root of 18115820 is about 4256.2683186096. The cubic root of 18115820 is about 262.6350386075.

The spelling of 18115820 in words is "eighteen million, one hundred fifteen thousand, eight hundred twenty".