18815139 has 16 divisors (see below), whose sum is σ = 31856640. Its totient is φ = 10751400.

The previous prime is 18815089. The next prime is 18815143. The reversal of 18815139 is 93151881.

It is not a de Polignac number, because 18815139 - 2¹² = 18811043 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18825139) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49587 + ... + 49964.

It is an arithmetic number, because the mean of its divisors is an integer number (1991040).

Almost surely, 2^18815139 is an apocalyptic number.

18815139 is a deficient number, since it is larger than the sum of its proper divisors (13041501).

18815139 is an equidigital number, since it uses as much as digits as its factorization.

18815139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99567 (or 99561 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 18815139 is about 4337.6421014187. The cubic root of 18815139 is about 265.9719334587.

The spelling of 18815139 in words is "eighteen million, eight hundred fifteen thousand, one hundred thirty-nine".