31855238021 has 2 divisors, whose sum is σ = 31855238022. Its totient is φ = 31855238020.

The previous prime is 31855238011. The next prime is 31855238029. The reversal of 31855238021 is 12083255813.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24581536225 + 7273701796 = 156785^2 + 85286^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31855238021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31855238029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15927619010 + 15927619011.

It is an arithmetic number, because the mean of its divisors is an integer number (15927619011).

Almost surely, 2^31855238021 is an apocalyptic number.

It is an amenable number.

31855238021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31855238021 is an equidigital number, since it uses as much as digits as its factorization.

31855238021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57600, while the sum is 38.

The spelling of 31855238021 in words is "thirty-one billion, eight hundred fifty-five million, two hundred thirty-eight thousand, twenty-one".