31996021 has 2 divisors, whose sum is σ = 31996022. Its totient is φ = 31996020.

The previous prime is 31995983. The next prime is 31996033. The reversal of 31996021 is 12069913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22905796 + 9090225 = 4786^2 + 3015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31996021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31996121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15998010 + 15998011.

It is an arithmetic number, because the mean of its divisors is an integer number (15998011).

Almost surely, 2^31996021 is an apocalyptic number.

It is an amenable number.

31996021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31996021 is an equidigital number, since it uses as much as digits as its factorization.

31996021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 31996021 is about 5656.5025413236. The cubic root of 31996021 is about 317.4670509549.

The spelling of 31996021 in words is "thirty-one million, nine hundred ninety-six thousand, twenty-one".