31991709818869 has 2 divisors, whose sum is σ = 31991709818870. Its totient is φ = 31991709818868.

The previous prime is 31991709818839. The next prime is 31991709818911. The reversal of 31991709818869 is 96881890719913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29922398798769 + 2069311020100 = 5470137^2 + 1438510^2 .

It is a cyclic number.

It is not a de Polignac number, because 31991709818869 - 2²³ = 31991701430261 is a prime.

It is a super-2 number, since 2×31991709818869² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31991709818819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995854909434 + 15995854909435.

It is an arithmetic number, because the mean of its divisors is an integer number (15995854909435).

Almost surely, 2^{31991709818869} is an apocalyptic number.

It is an amenable number.

31991709818869 is a deficient number, since it is larger than the sum of its proper divisors (1).

31991709818869 is an equidigital number, since it uses as much as digits as its factorization.

31991709818869 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 423263232, while the sum is 79.

The spelling of 31991709818869 in words is "thirty-one trillion, nine hundred ninety-one billion, seven hundred nine million, eight hundred eighteen thousand, eight hundred sixty-nine".