391322257 has 2 divisors, whose sum is σ = 391322258. Its totient is φ = 391322256.

The previous prime is 391322237. The next prime is 391322263. The reversal of 391322257 is 752223193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 334304656 + 57017601 = 18284^2 + 7551^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-391322257 is a prime.

It is not a weakly prime, because it can be changed into another prime (391322227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195661128 + 195661129.

It is an arithmetic number, because the mean of its divisors is an integer number (195661129).

Almost surely, 2^391322257 is an apocalyptic number.

It is an amenable number.

391322257 is a deficient number, since it is larger than the sum of its proper divisors (1).

391322257 is an equidigital number, since it uses as much as digits as its factorization.

391322257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 34.

The square root of 391322257 is about 19781.8668734778. The cubic root of 391322257 is about 731.4391182805.

The spelling of 391322257 in words is "three hundred ninety-one million, three hundred twenty-two thousand, two hundred fifty-seven".