21002120221021 has 2 divisors, whose sum is σ = 21002120221022. Its totient is φ = 21002120221020.

The previous prime is 21002120221007. The next prime is 21002120221097. The reversal of 21002120221021 is 12012202120012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13292951402500 + 7709168818521 = 3645950^2 + 2776539^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002120221021 - 2³³ = 20993530286429 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21002120220986 and 21002120221004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002120221321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060110510 + 10501060110511.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060110511).

Almost surely, 2^{21002120221021} is an apocalyptic number.

It is an amenable number.

21002120221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002120221021 is an equidigital number, since it uses as much as digits as its factorization.

21002120221021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21002120221021 its reverse (12012202120012), we get a palindrome (33014322341033).

The spelling of 21002120221021 in words is "twenty-one trillion, two billion, one hundred twenty million, two hundred twenty-one thousand, twenty-one".