20312221921 has 2 divisors, whose sum is σ = 20312221922. Its totient is φ = 20312221920.

The previous prime is 20312221901. The next prime is 20312222027. The reversal of 20312221921 is 12912221302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10396045521 + 9916176400 = 101961^2 + 99580^2 .

It is a cyclic number.

It is not a de Polignac number, because 20312221921 - 2¹⁷ = 20312090849 is a prime.

It is not a weakly prime, because it can be changed into another prime (20312221901) 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, 10156110960 + 10156110961.

It is an arithmetic number, because the mean of its divisors is an integer number (10156110961).

Almost surely, 2^20312221921 is an apocalyptic number.

It is an amenable number.

20312221921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20312221921 is an equidigital number, since it uses as much as digits as its factorization.

20312221921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The spelling of 20312221921 in words is "twenty billion, three hundred twelve million, two hundred twenty-one thousand, nine hundred twenty-one".