138931915 has 4 divisors (see below), whose sum is σ = 166718304. Its totient is φ = 111145528.

The previous prime is 138931913. The next prime is 138931927. The reversal of 138931915 is 519139831.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 138931915 - 2¹ = 138931913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138931913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13893187 + ... + 13893196.

It is an arithmetic number, because the mean of its divisors is an integer number (41679576).

Almost surely, 2^138931915 is an apocalyptic number.

138931915 is a deficient number, since it is larger than the sum of its proper divisors (27786389).

138931915 is an equidigital number, since it uses as much as digits as its factorization.

138931915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27786388.

The product of its digits is 29160, while the sum is 40.

The square root of 138931915 is about 11786.9383217187. The cubic root of 138931915 is about 517.9255556569.

The spelling of 138931915 in words is "one hundred thirty-eight million, nine hundred thirty-one thousand, nine hundred fifteen".