138723239 has 2 divisors, whose sum is σ = 138723240. Its totient is φ = 138723238.

The previous prime is 138723227. The next prime is 138723271. The reversal of 138723239 is 932327831.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138723239 - 2⁴ = 138723223 is a prime.

It is a super-2 number, since 2×138723239² = 38488274077302242, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138723839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69361619 + 69361620.

It is an arithmetic number, because the mean of its divisors is an integer number (69361620).

Almost surely, 2^138723239 is an apocalyptic number.

138723239 is a deficient number, since it is larger than the sum of its proper divisors (1).

138723239 is an equidigital number, since it uses as much as digits as its factorization.

138723239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 38.

The square root of 138723239 is about 11778.0829934247. The cubic root of 138723239 is about 517.6661173320. Note that the first 3 decimals are identical.

The spelling of 138723239 in words is "one hundred thirty-eight million, seven hundred twenty-three thousand, two hundred thirty-nine".