138911639 has 4 divisors (see below), whose sum is σ = 139570200. Its totient is φ = 138253080.

The previous prime is 138911623. The next prime is 138911681. The reversal of 138911639 is 936119831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 936119831 = 41 ⋅22832191.

It is a cyclic number.

It is not a de Polignac number, because 138911639 - 2⁴ = 138911623 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 138911596 and 138911605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138911609) 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, 328964 + ... + 329385.

It is an arithmetic number, because the mean of its divisors is an integer number (34892550).

Almost surely, 2^138911639 is an apocalyptic number.

138911639 is a deficient number, since it is larger than the sum of its proper divisors (658561).

138911639 is an equidigital number, since it uses as much as digits as its factorization.

138911639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658560.

The product of its digits is 34992, while the sum is 41.

The square root of 138911639 is about 11786.0781857240. The cubic root of 138911639 is about 517.9003587358.

The spelling of 138911639 in words is "one hundred thirty-eight million, nine hundred eleven thousand, six hundred thirty-nine".