31371311821 has 2 divisors, whose sum is σ = 31371311822. Its totient is φ = 31371311820.

The previous prime is 31371311809. The next prime is 31371311857. The reversal of 31371311821 is 12811317313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27438266025 + 3933045796 = 165645^2 + 62714^2 .

It is a cyclic number.

It is not a de Polignac number, because 31371311821 - 2¹⁹ = 31370787533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31371315821) 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, 15685655910 + 15685655911.

It is an arithmetic number, because the mean of its divisors is an integer number (15685655911).

Almost surely, 2^31371311821 is an apocalyptic number.

It is an amenable number.

31371311821 is a deficient number, since it is larger than the sum of its proper divisors (1).

31371311821 is an equidigital number, since it uses as much as digits as its factorization.

31371311821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 31.

The spelling of 31371311821 in words is "thirty-one billion, three hundred seventy-one million, three hundred eleven thousand, eight hundred twenty-one".