21202102021 has 2 divisors, whose sum is σ = 21202102022. Its totient is φ = 21202102020.

The previous prime is 21202102003. The next prime is 21202102049. The reversal of 21202102021 is 12020120212.

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., 16445241121 + 4756860900 = 128239^2 + 68970^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202102021 - 2⁹ = 21202101509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21202101992 and 21202102010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202102001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601051010 + 10601051011.

It is an arithmetic number, because the mean of its divisors is an integer number (10601051011).

Almost surely, 2^21202102021 is an apocalyptic number.

It is an amenable number.

21202102021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202102021 is an equidigital number, since it uses as much as digits as its factorization.

21202102021 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 13.

Adding to 21202102021 its reverse (12020120212), we get a palindrome (33222222233).

The spelling of 21202102021 in words is "twenty-one billion, two hundred two million, one hundred two thousand, twenty-one".