631391 has 2 divisors, whose sum is σ = 631392. Its totient is φ = 631390.

The previous prime is 631387. The next prime is 631399. The reversal of 631391 is 193136.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 631391 - 2² = 631387 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

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 631391.

It is not a weakly prime, because it can be changed into another prime (631399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315695 + 315696.

It is an arithmetic number, because the mean of its divisors is an integer number (315696).

2⁶³¹³⁹¹ is an apocalyptic number.

631391 is a deficient number, since it is larger than the sum of its proper divisors (1).

631391 is an equidigital number, since it uses as much as digits as its factorization.

631391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 23.

The square root of 631391 is about 794.6011578144. The cubic root of 631391 is about 85.7892351058.

The spelling of 631391 in words is "six hundred thirty-one thousand, three hundred ninety-one".