138439291 has 2 divisors, whose sum is σ = 138439292. Its totient is φ = 138439290.

The previous prime is 138439267. The next prime is 138439297. The reversal of 138439291 is 192934831.

It is a strong prime.

It is an emirp because it is prime and its reverse (192934831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138439291 - 2¹³ = 138431099 is a prime.

It is not a weakly prime, because it can be changed into another prime (138439297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69219645 + 69219646.

It is an arithmetic number, because the mean of its divisors is an integer number (69219646).

Almost surely, 2^138439291 is an apocalyptic number.

138439291 is a deficient number, since it is larger than the sum of its proper divisors (1).

138439291 is an equidigital number, since it uses as much as digits as its factorization.

138439291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 40.

The square root of 138439291 is about 11766.0227349772. The cubic root of 138439291 is about 517.3126782020.

The spelling of 138439291 in words is "one hundred thirty-eight million, four hundred thirty-nine thousand, two hundred ninety-one".