138640668 has 24 divisors (see below), whose sum is σ = 323686272. Its totient is φ = 46186224.

The previous prime is 138640657. The next prime is 138640669. The reversal of 138640668 is 866046831.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138640669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34921 + ... + 38687.

It is an arithmetic number, because the mean of its divisors is an integer number (13486928).

Almost surely, 2^138640668 is an apocalyptic number.

It is an amenable number.

138640668 is an abundant number, since it is smaller than the sum of its proper divisors (185045604).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

138640668 is a wasteful number, since it uses less digits than its factorization.

138640668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6841 (or 6839 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 42.

The square root of 138640668 is about 11774.5771898612. The cubic root of 138640668 is about 517.5633883472.

The spelling of 138640668 in words is "one hundred thirty-eight million, six hundred forty thousand, six hundred sixty-eight".