138640868 has 12 divisors (see below), whose sum is σ = 242740092. Its totient is φ = 69286560.

The previous prime is 138640867. The next prime is 138640871. The reversal of 138640868 is 868046831.

138640868 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 6666724 + 131974144 = 2582^2 + 11488^2 .

It is not an unprimeable number, because it can be changed into a prime (138640867) 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, 2246 + ... + 16802.

It is an arithmetic number, because the mean of its divisors is an integer number (20228341).

Almost surely, 2^138640868 is an apocalyptic number.

It is an amenable number.

138640868 is a deficient number, since it is larger than the sum of its proper divisors (104099224).

138640868 is a wasteful number, since it uses less digits than its factorization.

138640868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16942 (or 16940 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 44.

The square root of 138640868 is about 11774.5856827321. The cubic root of 138640868 is about 517.5636372223.

The spelling of 138640868 in words is "one hundred thirty-eight million, six hundred forty thousand, eight hundred sixty-eight".