31536386821 has 2 divisors, whose sum is σ = 31536386822. Its totient is φ = 31536386820.

The previous prime is 31536386771. The next prime is 31536386837. The reversal of 31536386821 is 12868363513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27022428225 + 4513958596 = 164385^2 + 67186^2 .

It is a cyclic number.

It is not a de Polignac number, because 31536386821 - 2⁹ = 31536386309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31536383821) 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, 15768193410 + 15768193411.

It is an arithmetic number, because the mean of its divisors is an integer number (15768193411).

Almost surely, 2^31536386821 is an apocalyptic number.

It is an amenable number.

31536386821 is a deficient number, since it is larger than the sum of its proper divisors (1).

31536386821 is an equidigital number, since it uses as much as digits as its factorization.

31536386821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 622080, while the sum is 46.

The spelling of 31536386821 in words is "thirty-one billion, five hundred thirty-six million, three hundred eighty-six thousand, eight hundred twenty-one".