31813766861 has 2 divisors, whose sum is σ = 31813766862. Its totient is φ = 31813766860.

The previous prime is 31813766797. The next prime is 31813766863. The reversal of 31813766861 is 16866731813.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31393106761 + 420660100 = 177181^2 + 20510^2 .

It is a cyclic number.

It is not a de Polignac number, because 31813766861 - 2⁶ = 31813766797 is a prime.

Together with 31813766863, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31813766863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15906883430 + 15906883431.

It is an arithmetic number, because the mean of its divisors is an integer number (15906883431).

Almost surely, 2^31813766861 is an apocalyptic number.

It is an amenable number.

31813766861 is a deficient number, since it is larger than the sum of its proper divisors (1).

31813766861 is an equidigital number, since it uses as much as digits as its factorization.

31813766861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 870912, while the sum is 50.

The spelling of 31813766861 in words is "thirty-one billion, eight hundred thirteen million, seven hundred sixty-six thousand, eight hundred sixty-one".