138185909 has 12 divisors (see below), whose sum is σ = 145998636. Its totient is φ = 130766592.

The previous prime is 138185891. The next prime is 138185977. The reversal of 138185909 is 909581831.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 59367025 + 78818884 = 7705^2 + 8878^2 .

It is not a de Polignac number, because 138185909 - 2¹⁶ = 138120373 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 138185909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138185209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49967 + ... + 52659.

It is an arithmetic number, because the mean of its divisors is an integer number (12166553).

Almost surely, 2^138185909 is an apocalyptic number.

It is an amenable number.

138185909 is a deficient number, since it is larger than the sum of its proper divisors (7812727).

138185909 is an equidigital number, since it uses as much as digits as its factorization.

138185909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2836 (or 2813 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 44.

The square root of 138185909 is about 11755.2502738138. The cubic root of 138185909 is about 516.9968772688.

The spelling of 138185909 in words is "one hundred thirty-eight million, one hundred eighty-five thousand, nine hundred nine".