21212221102021 has 2 divisors, whose sum is σ = 21212221102022. Its totient is φ = 21212221102020.

The previous prime is 21212221101991. The next prime is 21212221102049. The reversal of 21212221102021 is 12020112221212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19563857841025 + 1648363260996 = 4423105^2 + 1283886^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212221102021 - 2²¹ = 21212219004869 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212221102021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212221102081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606110551010 + 10606110551011.

It is an arithmetic number, because the mean of its divisors is an integer number (10606110551011).

Almost surely, 2^{21212221102021} is an apocalyptic number.

It is an amenable number.

21212221102021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212221102021 is an equidigital number, since it uses as much as digits as its factorization.

21212221102021 is an evil number, because the sum of its binary digits is even.

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

Adding to 21212221102021 its reverse (12020112221212), we get a palindrome (33232333323233).

The spelling of 21212221102021 in words is "twenty-one trillion, two hundred twelve billion, two hundred twenty-one million, one hundred two thousand, twenty-one".