138391668 has 36 divisors (see below), whose sum is σ = 368236960. Its totient is φ = 43702416.

The previous prime is 138391661. The next prime is 138391681. The reversal of 138391668 is 866193831.

It is a happy number.

138391668 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138391661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 100480 + ... + 101847.

Almost surely, 2^138391668 is an apocalyptic number.

138391668 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

138391668 is an abundant number, since it is smaller than the sum of its proper divisors (229845292).

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

138391668 is a wasteful number, since it uses less digits than its factorization.

138391668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202356 (or 202351 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 138391668 is about 11763.9988099285. The cubic root of 138391668 is about 517.2533530230.

The spelling of 138391668 in words is "one hundred thirty-eight million, three hundred ninety-one thousand, six hundred sixty-eight".