138815815 has 8 divisors (see below), whose sum is σ = 166648608. Its totient is φ = 111006240.

The previous prime is 138815777. The next prime is 138815857. The reversal of 138815815 is 518518831.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138815815 - 2²³ = 130427207 is a prime.

It is a super-2 number, since 2×138815815² = 38539660988228450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12750 + ... + 20980.

It is an arithmetic number, because the mean of its divisors is an integer number (20831076).

Almost surely, 2^138815815 is an apocalyptic number.

138815815 is a deficient number, since it is larger than the sum of its proper divisors (27832793).

138815815 is an equidigital number, since it uses as much as digits as its factorization.

138815815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11609.

The product of its digits is 38400, while the sum is 40.

The square root of 138815815 is about 11782.0123493400. The cubic root of 138815815 is about 517.7812453675.

The spelling of 138815815 in words is "one hundred thirty-eight million, eight hundred fifteen thousand, eight hundred fifteen".