21210310021 has 2 divisors, whose sum is σ = 21210310022. Its totient is φ = 21210310020.

The previous prime is 21210310007. The next prime is 21210310027. The reversal of 21210310021 is 12001301212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14438665921 + 6771644100 = 120161^2 + 82290^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210310021 - 2⁹ = 21210309509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21210309983 and 21210310010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210310027) 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, 10605155010 + 10605155011.

It is an arithmetic number, because the mean of its divisors is an integer number (10605155011).

Almost surely, 2^21210310021 is an apocalyptic number.

It is an amenable number.

21210310021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210310021 is an equidigital number, since it uses as much as digits as its factorization.

21210310021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21210310021 its reverse (12001301212), we get a palindrome (33211611233).

The spelling of 21210310021 in words is "twenty-one billion, two hundred ten million, three hundred ten thousand, twenty-one".