138509257 has 2 divisors, whose sum is σ = 138509258. Its totient is φ = 138509256.

The previous prime is 138509237. The next prime is 138509291. The reversal of 138509257 is 752905831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 128799801 + 9709456 = 11349^2 + 3116^2 .

It is a cyclic number.

It is not a de Polignac number, because 138509257 - 2¹⁵ = 138476489 is a prime.

It is not a weakly prime, because it can be changed into another prime (138509227) 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 as a sum of consecutive naturals, namely, 69254628 + 69254629.

It is an arithmetic number, because the mean of its divisors is an integer number (69254629).

Almost surely, 2^138509257 is an apocalyptic number.

It is an amenable number.

138509257 is a deficient number, since it is larger than the sum of its proper divisors (1).

138509257 is an equidigital number, since it uses as much as digits as its factorization.

138509257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 75600, while the sum is 40.

The square root of 138509257 is about 11768.9955816119. The cubic root of 138509257 is about 517.3998119506.

The spelling of 138509257 in words is "one hundred thirty-eight million, five hundred nine thousand, two hundred fifty-seven".