31812311621 has 2 divisors, whose sum is σ = 31812311622. Its totient is φ = 31812311620.

The previous prime is 31812311551. The next prime is 31812311623. The reversal of 31812311621 is 12611321813.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18491920225 + 13320391396 = 135985^2 + 115414^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31812311621 is a prime.

It is a super-3 number, since 3×31812311621³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 31812311623, 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 (31812311623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15906155810 + 15906155811.

It is an arithmetic number, because the mean of its divisors is an integer number (15906155811).

Almost surely, 2^31812311621 is an apocalyptic number.

It is an amenable number.

31812311621 is a deficient number, since it is larger than the sum of its proper divisors (1).

31812311621 is an equidigital number, since it uses as much as digits as its factorization.

31812311621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The spelling of 31812311621 in words is "thirty-one billion, eight hundred twelve million, three hundred eleven thousand, six hundred twenty-one".