138509291 has 2 divisors, whose sum is σ = 138509292. Its totient is φ = 138509290.

The previous prime is 138509257. The next prime is 138509303. The reversal of 138509291 is 192905831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138509291 - 2⁶ = 138509227 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138502291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69254645 + 69254646.

It is an arithmetic number, because the mean of its divisors is an integer number (69254646).

Almost surely, 2^138509291 is an apocalyptic number.

138509291 is a deficient number, since it is larger than the sum of its proper divisors (1).

138509291 is an equidigital number, since it uses as much as digits as its factorization.

138509291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 138509291 is about 11768.9970260851. The cubic root of 138509291 is about 517.3998542861.

The spelling of 138509291 in words is "one hundred thirty-eight million, five hundred nine thousand, two hundred ninety-one".