138965639 has 4 divisors (see below), whose sum is σ = 146279640. Its totient is φ = 131651640.

The previous prime is 138965623. The next prime is 138965641. The reversal of 138965639 is 936569831.

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 138965639 - 2⁴ = 138965623 is a prime.

It is a super-2 number, since 2×138965639² = 38622897645356642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138965689) 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, 3656972 + ... + 3657009.

It is an arithmetic number, because the mean of its divisors is an integer number (36569910).

Almost surely, 2^138965639 is an apocalyptic number.

138965639 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

138965639 is a deficient number, since it is larger than the sum of its proper divisors (7314001).

138965639 is an equidigital number, since it uses as much as digits as its factorization.

138965639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7314000.

The product of its digits is 1049760, while the sum is 50.

The square root of 138965639 is about 11788.3688014924. The cubic root of 138965639 is about 517.9674589358.

The spelling of 138965639 in words is "one hundred thirty-eight million, nine hundred sixty-five thousand, six hundred thirty-nine".