312531991 has 2 divisors, whose sum is σ = 312531992. Its totient is φ = 312531990.

The previous prime is 312531977. The next prime is 312532021. The reversal of 312531991 is 199135213.

It is a weak prime.

It is an emirp because it is prime and its reverse (199135213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 312531991 - 2⁵ = 312531959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (312531391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 156265995 + 156265996.

It is an arithmetic number, because the mean of its divisors is an integer number (156265996).

Almost surely, 2^312531991 is an apocalyptic number.

312531991 is a deficient number, since it is larger than the sum of its proper divisors (1).

312531991 is an equidigital number, since it uses as much as digits as its factorization.

312531991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7290, while the sum is 34.

The square root of 312531991 is about 17678.5743486289. The cubic root of 312531991 is about 678.6275598743.

The spelling of 312531991 in words is "three hundred twelve million, five hundred thirty-one thousand, nine hundred ninety-one".