21021220001021 has 2 divisors, whose sum is σ = 21021220001022. Its totient is φ = 21021220001020.

The previous prime is 21021220001009. The next prime is 21021220001039. The reversal of 21021220001021 is 12010002212012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12442120420921 + 8579099580100 = 3527339^2 + 2929010^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021220001021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021220000987 and 21021220001005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021220004021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510610000510 + 10510610000511.

It is an arithmetic number, because the mean of its divisors is an integer number (10510610000511).

Almost surely, 2^{21021220001021} is an apocalyptic number.

It is an amenable number.

21021220001021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021220001021 is an equidigital number, since it uses as much as digits as its factorization.

21021220001021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21021220001021 its reverse (12010002212012), we get a palindrome (33031222213033).

The spelling of 21021220001021 in words is "twenty-one trillion, twenty-one billion, two hundred twenty million, one thousand, twenty-one".