138079891 has 2 divisors, whose sum is σ = 138079892. Its totient is φ = 138079890.

The previous prime is 138079889. The next prime is 138079951. The reversal of 138079891 is 198970831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138079891 - 2¹ = 138079889 is a prime.

Together with 138079889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (138079801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69039945 + 69039946.

It is an arithmetic number, because the mean of its divisors is an integer number (69039946).

Almost surely, 2^138079891 is an apocalyptic number.

138079891 is a deficient number, since it is larger than the sum of its proper divisors (1).

138079891 is an equidigital number, since it uses as much as digits as its factorization.

138079891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108864, while the sum is 46.

The square root of 138079891 is about 11750.7400192499. The cubic root of 138079891 is about 516.8646278990.

The spelling of 138079891 in words is "one hundred thirty-eight million, seventy-nine thousand, eight hundred ninety-one".