138268391 has 2 divisors, whose sum is σ = 138268392. Its totient is φ = 138268390.

The previous prime is 138268379. The next prime is 138268393. The reversal of 138268391 is 193862831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138268391 - 2¹⁸ = 138006247 is a prime.

Together with 138268393, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_7819691 and since 138268391 and 7819691 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138268393) 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, 69134195 + 69134196.

It is an arithmetic number, because the mean of its divisors is an integer number (69134196).

Almost surely, 2^138268391 is an apocalyptic number.

138268391 is a deficient number, since it is larger than the sum of its proper divisors (1).

138268391 is an equidigital number, since it uses as much as digits as its factorization.

138268391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 41.

The square root of 138268391 is about 11758.7580551689. The cubic root of 138268391 is about 517.0997204968.

The spelling of 138268391 in words is "one hundred thirty-eight million, two hundred sixty-eight thousand, three hundred ninety-one".