138973639 has 4 divisors (see below), whose sum is σ = 158827024. Its totient is φ = 119120256.

The previous prime is 138973621. The next prime is 138973643. The reversal of 138973639 is 936379831.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 138973639 - 2⁵ = 138973607 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 138973592 and 138973601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138973609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9926682 + ... + 9926695.

It is an arithmetic number, because the mean of its divisors is an integer number (39706756).

Almost surely, 2^138973639 is an apocalyptic number.

138973639 is a deficient number, since it is larger than the sum of its proper divisors (19853385).

138973639 is an equidigital number, since it uses as much as digits as its factorization.

138973639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19853384.

The product of its digits is 734832, while the sum is 49.

The square root of 138973639 is about 11788.7081141234. The cubic root of 138973639 is about 517.9773982277.

The spelling of 138973639 in words is "one hundred thirty-eight million, nine hundred seventy-three thousand, six hundred thirty-nine".