138220891 has 2 divisors, whose sum is σ = 138220892. Its totient is φ = 138220890.

The previous prime is 138220889. The next prime is 138220939. The reversal of 138220891 is 198022831.

138220891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138220891 - 2¹ = 138220889 is a prime.

Together with 138220889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (138290891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69110445 + 69110446.

It is an arithmetic number, because the mean of its divisors is an integer number (69110446).

Almost surely, 2^138220891 is an apocalyptic number.

138220891 is a deficient number, since it is larger than the sum of its proper divisors (1).

138220891 is an equidigital number, since it uses as much as digits as its factorization.

138220891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 138220891 is about 11756.7381105475. The cubic root of 138220891 is about 517.0404998035.

The spelling of 138220891 in words is "one hundred thirty-eight million, two hundred twenty thousand, eight hundred ninety-one".