31947639391 has 2 divisors, whose sum is σ = 31947639392. Its totient is φ = 31947639390.

The previous prime is 31947639359. The next prime is 31947639407. The reversal of 31947639391 is 19393674913.

It is a strong prime.

It is an emirp because it is prime and its reverse (19393674913) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31947639391 - 2⁵ = 31947639359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31947639301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15973819695 + 15973819696.

It is an arithmetic number, because the mean of its divisors is an integer number (15973819696).

Almost surely, 2^31947639391 is an apocalyptic number.

31947639391 is a deficient number, since it is larger than the sum of its proper divisors (1).

31947639391 is an equidigital number, since it uses as much as digits as its factorization.

31947639391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3306744, while the sum is 55.

The spelling of 31947639391 in words is "thirty-one billion, nine hundred forty-seven million, six hundred thirty-nine thousand, three hundred ninety-one".