318638891 has 2 divisors, whose sum is σ = 318638892. Its totient is φ = 318638890.

The previous prime is 318638861. The next prime is 318638893. The reversal of 318638891 is 198836813.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-318638891 is a prime.

It is a Sophie Germain prime.

Together with 318638893, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (318638893) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159319445 + 159319446.

It is an arithmetic number, because the mean of its divisors is an integer number (159319446).

Almost surely, 2^318638891 is an apocalyptic number.

318638891 is a deficient number, since it is larger than the sum of its proper divisors (1).

318638891 is an equidigital number, since it uses as much as digits as its factorization.

318638891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 47.

The square root of 318638891 is about 17850.4591257480. The cubic root of 318638891 is about 683.0192239208.

The spelling of 318638891 in words is "three hundred eighteen million, six hundred thirty-eight thousand, eight hundred ninety-one".