18115209 has 24 divisors (see below), whose sum is σ = 30019392. Its totient is φ = 10311840.

The previous prime is 18115193. The next prime is 18115211. The reversal of 18115209 is 90251181.

It is not a de Polignac number, because 18115209 - 2⁴ = 18115193 is a prime.

It is a super-2 number, since 2×18115209² = 656321594227362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18115219) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26182 + ... + 26864.

It is an arithmetic number, because the mean of its divisors is an integer number (1250808).

Almost surely, 2^18115209 is an apocalyptic number.

It is an amenable number.

18115209 is a deficient number, since it is larger than the sum of its proper divisors (11904183).

18115209 is a wasteful number, since it uses less digits than its factorization.

18115209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117 (or 1114 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 18115209 is about 4256.1965415145. The cubic root of 18115209 is about 262.6320859062.

The spelling of 18115209 in words is "eighteen million, one hundred fifteen thousand, two hundred nine".