138231491 has 2 divisors, whose sum is σ = 138231492. Its totient is φ = 138231490.

The previous prime is 138231463. The next prime is 138231521. The reversal of 138231491 is 194132831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138231491 - 2⁶ = 138231427 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138231421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69115745 + 69115746.

It is an arithmetic number, because the mean of its divisors is an integer number (69115746).

Almost surely, 2^138231491 is an apocalyptic number.

138231491 is a deficient number, since it is larger than the sum of its proper divisors (1).

138231491 is an equidigital number, since it uses as much as digits as its factorization.

138231491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 138231491 is about 11757.1889072176. The cubic root of 138231491 is about 517.0537165446.

The spelling of 138231491 in words is "one hundred thirty-eight million, two hundred thirty-one thousand, four hundred ninety-one".