138231421 has 2 divisors, whose sum is σ = 138231422. Its totient is φ = 138231420.

The previous prime is 138231397. The next prime is 138231427. The reversal of 138231421 is 124132831.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138062500 + 168921 = 11750^2 + 411^2 .

It is a cyclic number.

It is not a de Polignac number, because 138231421 - 2¹⁵ = 138198653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138231427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69115710 + 69115711.

It is an arithmetic number, because the mean of its divisors is an integer number (69115711).

Almost surely, 2^138231421 is an apocalyptic number.

It is an amenable number.

138231421 is a deficient number, since it is larger than the sum of its proper divisors (1).

138231421 is an equidigital number, since it uses as much as digits as its factorization.

138231421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 25.

The square root of 138231421 is about 11757.1859303151. The cubic root of 138231421 is about 517.0536292665.

The spelling of 138231421 in words is "one hundred thirty-eight million, two hundred thirty-one thousand, four hundred twenty-one".