313991 has 2 divisors, whose sum is σ = 313992. Its totient is φ = 313990.

The previous prime is 313987. The next prime is 313993. The reversal of 313991 is 199313.

It is a strong prime.

It is an emirp because it is prime and its reverse (199313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 313991 - 2² = 313987 is a prime.

Together with 313993, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 313991.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 313991.

It is not a weakly prime, because it can be changed into another prime (313993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 156995 + 156996.

It is an arithmetic number, because the mean of its divisors is an integer number (156996).

2³¹³⁹⁹¹ is an apocalyptic number.

313991 is a deficient number, since it is larger than the sum of its proper divisors (1).

313991 is an equidigital number, since it uses as much as digits as its factorization.

313991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 729, while the sum is 26.

The square root of 313991 is about 560.3489983930. The cubic root of 313991 is about 67.9681944685.

The spelling of 313991 in words is "three hundred thirteen thousand, nine hundred ninety-one".