138979591 has 4 divisors (see below), whose sum is σ = 139048272. Its totient is φ = 138910912.

The previous prime is 138979579. The next prime is 138979609. The reversal of 138979591 is 195979831.

It is a happy number.

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 138979591 - 2¹⁷ = 138848519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138979531) 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, 31210 + ... + 35383.

It is an arithmetic number, because the mean of its divisors is an integer number (34762068).

Almost surely, 2^138979591 is an apocalyptic number.

138979591 is a deficient number, since it is larger than the sum of its proper divisors (68681).

138979591 is an equidigital number, since it uses as much as digits as its factorization.

138979591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68680.

The product of its digits is 612360, while the sum is 52.

The square root of 138979591 is about 11788.9605563849. The cubic root of 138979591 is about 517.9847928134.

The spelling of 138979591 in words is "one hundred thirty-eight million, nine hundred seventy-nine thousand, five hundred ninety-one".