138388639 has 8 divisors (see below), whose sum is σ = 141508080. Its totient is φ = 135303936.

The previous prime is 138388597. The next prime is 138388651. The reversal of 138388639 is 936883831.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 138388639 - 2⁹ = 138388127 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 138388592 and 138388601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138388669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 544 + ... + 16645.

It is an arithmetic number, because the mean of its divisors is an integer number (17688510).

Almost surely, 2^138388639 is an apocalyptic number.

138388639 is a deficient number, since it is larger than the sum of its proper divisors (3119441).

138388639 is an equidigital number, since it uses as much as digits as its factorization.

138388639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17369.

The product of its digits is 746496, while the sum is 49.

The square root of 138388639 is about 11763.8700689867. The cubic root of 138388639 is about 517.2495792606.

The spelling of 138388639 in words is "one hundred thirty-eight million, three hundred eighty-eight thousand, six hundred thirty-nine".