138665904 has 80 divisors (see below), whose sum is σ = 387475200. Its totient is φ = 42478848.

The previous prime is 138665903. The next prime is 138665921. The reversal of 138665904 is 409566831.

138665904 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (138665903) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 223707 + ... + 224325.

It is an arithmetic number, because the mean of its divisors is an integer number (4843440).

Almost surely, 2^138665904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138665904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (193737600).

138665904 is an abundant number, since it is smaller than the sum of its proper divisors (248809296).

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

138665904 is a wasteful number, since it uses less digits than its factorization.

138665904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1002 (or 996 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 42.

The square root of 138665904 is about 11775.6487719361. The cubic root of 138665904 is about 517.5947895165.

The spelling of 138665904 in words is "one hundred thirty-eight million, six hundred sixty-five thousand, nine hundred four".