31221013639 has 2 divisors, whose sum is σ = 31221013640. Its totient is φ = 31221013638.

The previous prime is 31221013627. The next prime is 31221013679. The reversal of 31221013639 is 93631012213.

It is a weak prime.

It is an emirp because it is prime and its reverse (93631012213) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31221013639 - 2¹⁵ = 31220980871 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31221013639.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31221013609) 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, 15610506819 + 15610506820.

It is an arithmetic number, because the mean of its divisors is an integer number (15610506820).

Almost surely, 2^31221013639 is an apocalyptic number.

31221013639 is a deficient number, since it is larger than the sum of its proper divisors (1).

31221013639 is an equidigital number, since it uses as much as digits as its factorization.

31221013639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 31.

The spelling of 31221013639 in words is "thirty-one billion, two hundred twenty-one million, thirteen thousand, six hundred thirty-nine".