138257321 has 2 divisors, whose sum is σ = 138257322. Its totient is φ = 138257320.

The previous prime is 138257263. The next prime is 138257351. The reversal of 138257321 is 123752831.

138257321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79566400 + 58690921 = 8920^2 + 7661^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138257321 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138257351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69128660 + 69128661.

It is an arithmetic number, because the mean of its divisors is an integer number (69128661).

Almost surely, 2^138257321 is an apocalyptic number.

It is an amenable number.

138257321 is a deficient number, since it is larger than the sum of its proper divisors (1).

138257321 is an equidigital number, since it uses as much as digits as its factorization.

138257321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 32.

The square root of 138257321 is about 11758.2873327709. The cubic root of 138257321 is about 517.0859201706.

The spelling of 138257321 in words is "one hundred thirty-eight million, two hundred fifty-seven thousand, three hundred twenty-one".