21222202021 has 2 divisors, whose sum is σ = 21222202022. Its totient is φ = 21222202020.

The previous prime is 21222201989. The next prime is 21222202049. The reversal of 21222202021 is 12020222212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20942141796 + 280060225 = 144714^2 + 16735^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222202021 - 2⁵ = 21222201989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21222201986 and 21222202004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21222202321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611101010 + 10611101011.

It is an arithmetic number, because the mean of its divisors is an integer number (10611101011).

Almost surely, 2^21222202021 is an apocalyptic number.

It is an amenable number.

21222202021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21222202021 is an equidigital number, since it uses as much as digits as its factorization.

21222202021 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 16.

Adding to 21222202021 its reverse (12020222212), we get a palindrome (33242424233).

The spelling of 21222202021 in words is "twenty-one billion, two hundred twenty-two million, two hundred two thousand, twenty-one".