21002122211221 has 2 divisors, whose sum is σ = 21002122211222. Its totient is φ = 21002122211220.

The previous prime is 21002122211177. The next prime is 21002122211233. The reversal of 21002122211221 is 12211222120012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20998261452996 + 3860758225 = 4582386^2 + 62135^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002122211221 - 2⁷ = 21002122211093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002122211281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501061105610 + 10501061105611.

It is an arithmetic number, because the mean of its divisors is an integer number (10501061105611).

Almost surely, 2^{21002122211221} is an apocalyptic number.

It is an amenable number.

21002122211221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002122211221 is an equidigital number, since it uses as much as digits as its factorization.

21002122211221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21002122211221 its reverse (12211222120012), we get a palindrome (33213344331233).

The spelling of 21002122211221 in words is "twenty-one trillion, two billion, one hundred twenty-two million, two hundred eleven thousand, two hundred twenty-one".