31978036613 has 2 divisors, whose sum is σ = 31978036614. Its totient is φ = 31978036612.

The previous prime is 31978036589. The next prime is 31978036619. The reversal of 31978036613 is 31663087913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23054778244 + 8923258369 = 151838^2 + 94463^2 .

It is a cyclic number.

It is not a de Polignac number, because 31978036613 - 2⁸ = 31978036357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31978036619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15989018306 + 15989018307.

It is an arithmetic number, because the mean of its divisors is an integer number (15989018307).

Almost surely, 2^31978036613 is an apocalyptic number.

It is an amenable number.

31978036613 is a deficient number, since it is larger than the sum of its proper divisors (1).

31978036613 is an equidigital number, since it uses as much as digits as its factorization.

31978036613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 489888, while the sum is 47.

The spelling of 31978036613 in words is "thirty-one billion, nine hundred seventy-eight million, thirty-six thousand, six hundred thirteen".