391856317 has 2 divisors, whose sum is σ = 391856318. Its totient is φ = 391856316.

The previous prime is 391856303. The next prime is 391856407. The reversal of 391856317 is 713658193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 390023001 + 1833316 = 19749^2 + 1354^2 .

It is an emirp because it is prime and its reverse (713658193) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-391856317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391856917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195928158 + 195928159.

It is an arithmetic number, because the mean of its divisors is an integer number (195928159).

Almost surely, 2^391856317 is an apocalyptic number.

It is an amenable number.

391856317 is a deficient number, since it is larger than the sum of its proper divisors (1).

391856317 is an equidigital number, since it uses as much as digits as its factorization.

391856317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 43.

The square root of 391856317 is about 19795.3609969609. The cubic root of 391856317 is about 731.7717127061.

The spelling of 391856317 in words is "three hundred ninety-one million, eight hundred fifty-six thousand, three hundred seventeen".