12821531620021 has 2 divisors, whose sum is σ = 12821531620022. Its totient is φ = 12821531620020.

The previous prime is 12821531620013. The next prime is 12821531620043. The reversal of 12821531620021 is 12002613512821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12697028497521 + 124503122500 = 3563289^2 + 352850^2 .

It is a cyclic number.

It is not a de Polignac number, because 12821531620021 - 2³ = 12821531620013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12821531630021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6410765810010 + 6410765810011.

It is an arithmetic number, because the mean of its divisors is an integer number (6410765810011).

Almost surely, 2^{12821531620021} is an apocalyptic number.

It is an amenable number.

12821531620021 is a deficient number, since it is larger than the sum of its proper divisors (1).

12821531620021 is an equidigital number, since it uses as much as digits as its factorization.

12821531620021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 34.

The spelling of 12821531620021 in words is "twelve trillion, eight hundred twenty-one billion, five hundred thirty-one million, six hundred twenty thousand, twenty-one".