138902639 has 4 divisors (see below), whose sum is σ = 138937320. Its totient is φ = 138867960.

The previous prime is 138902633. The next prime is 138902641. The reversal of 138902639 is 936209831.

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 138902639 - 2¹⁶ = 138837103 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 138902596 and 138902605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138902633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10409 + ... + 19650.

It is an arithmetic number, because the mean of its divisors is an integer number (34734330).

Almost surely, 2^138902639 is an apocalyptic number.

138902639 is a deficient number, since it is larger than the sum of its proper divisors (34681).

138902639 is an equidigital number, since it uses as much as digits as its factorization.

138902639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34680.

The product of its (nonzero) digits is 69984, while the sum is 41.

The square root of 138902639 is about 11785.6963731466. The cubic root of 138902639 is about 517.8891736786.

The spelling of 138902639 in words is "one hundred thirty-eight million, nine hundred two thousand, six hundred thirty-nine".