138713257 has 2 divisors, whose sum is σ = 138713258. Its totient is φ = 138713256.

The previous prime is 138713233. The next prime is 138713261. The reversal of 138713257 is 752317831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138556441 + 156816 = 11771^2 + 396^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138713257 is a prime.

It is not a weakly prime, because it can be changed into another prime (138713287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69356628 + 69356629.

It is an arithmetic number, because the mean of its divisors is an integer number (69356629).

Almost surely, 2^138713257 is an apocalyptic number.

It is an amenable number.

138713257 is a deficient number, since it is larger than the sum of its proper divisors (1).

138713257 is an equidigital number, since it uses as much as digits as its factorization.

138713257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 37.

The square root of 138713257 is about 11777.6592326319. The cubic root of 138713257 is about 517.6537006017.

The spelling of 138713257 in words is "one hundred thirty-eight million, seven hundred thirteen thousand, two hundred fifty-seven".