138944257 has 2 divisors, whose sum is σ = 138944258. Its totient is φ = 138944256.

The previous prime is 138944243. The next prime is 138944279. The reversal of 138944257 is 752449831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 128504896 + 10439361 = 11336^2 + 3231^2 .

It is a cyclic number.

It is not a de Polignac number, because 138944257 - 2¹⁹ = 138419969 is a prime.

It is not a weakly prime, because it can be changed into another prime (138944557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69472128 + 69472129.

It is an arithmetic number, because the mean of its divisors is an integer number (69472129).

Almost surely, 2^138944257 is an apocalyptic number.

It is an amenable number.

138944257 is a deficient number, since it is larger than the sum of its proper divisors (1).

138944257 is an equidigital number, since it uses as much as digits as its factorization.

138944257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 43.

The square root of 138944257 is about 11787.4618557177. The cubic root of 138944257 is about 517.9408918209.

The spelling of 138944257 in words is "one hundred thirty-eight million, nine hundred forty-four thousand, two hundred fifty-seven".