631401391 has 2 divisors, whose sum is σ = 631401392. Its totient is φ = 631401390.

The previous prime is 631401389. The next prime is 631401409. The reversal of 631401391 is 193104136.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 631401391 - 2¹ = 631401389 is a prime.

Together with 631401389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (631401371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315700695 + 315700696.

It is an arithmetic number, because the mean of its divisors is an integer number (315700696).

Almost surely, 2^631401391 is an apocalyptic number.

631401391 is a deficient number, since it is larger than the sum of its proper divisors (1).

631401391 is an equidigital number, since it uses as much as digits as its factorization.

631401391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 631401391 is about 25127.7016656916. The cubic root of 631401391 is about 857.8970572336.

The spelling of 631401391 in words is "six hundred thirty-one million, four hundred one thousand, three hundred ninety-one".