138066391 has 2 divisors, whose sum is σ = 138066392. Its totient is φ = 138066390.

The previous prime is 138066371. The next prime is 138066403. The reversal of 138066391 is 193660831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138066391 - 2²⁵ = 104511959 is a prime.

It is a super-4 number, since 4×138066391⁴ (a number of 34 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 138066391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138066301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69033195 + 69033196.

It is an arithmetic number, because the mean of its divisors is an integer number (69033196).

Almost surely, 2^138066391 is an apocalyptic number.

138066391 is a deficient number, since it is larger than the sum of its proper divisors (1).

138066391 is an equidigital number, since it uses as much as digits as its factorization.

138066391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 138066391 is about 11750.1655733015. The cubic root of 138066391 is about 516.8477828203.

The spelling of 138066391 in words is "one hundred thirty-eight million, sixty-six thousand, three hundred ninety-one".