138388421 has 2 divisors, whose sum is σ = 138388422. Its totient is φ = 138388420.

The previous prime is 138388403. The next prime is 138388427. The reversal of 138388421 is 124883831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 112996900 + 25391521 = 10630^2 + 5039^2 .

It is a cyclic number.

It is not a de Polignac number, because 138388421 - 2⁶ = 138388357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138388427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69194210 + 69194211.

It is an arithmetic number, because the mean of its divisors is an integer number (69194211).

Almost surely, 2^138388421 is an apocalyptic number.

It is an amenable number.

138388421 is a deficient number, since it is larger than the sum of its proper divisors (1).

138388421 is an equidigital number, since it uses as much as digits as its factorization.

138388421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36864, while the sum is 38.

The square root of 138388421 is about 11763.8608033247. The cubic root of 138388421 is about 517.2493076572.

The spelling of 138388421 in words is "one hundred thirty-eight million, three hundred eighty-eight thousand, four hundred twenty-one".