21321220000021 has 2 divisors, whose sum is σ = 21321220000022. Its totient is φ = 21321220000020.

The previous prime is 21321219999979. The next prime is 21321220000027. The reversal of 21321220000021 is 12000002212312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21126663140625 + 194556859396 = 4596375^2 + 441086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321220000021 - 2⁹ = 21321219999509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321220000027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660610000010 + 10660610000011.

It is an arithmetic number, because the mean of its divisors is an integer number (10660610000011).

Almost surely, 2^{21321220000021} is an apocalyptic number.

It is an amenable number.

21321220000021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321220000021 is an equidigital number, since it uses as much as digits as its factorization.

21321220000021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21321220000021 its reverse (12000002212312), we get a palindrome (33321222212333).

The spelling of 21321220000021 in words is "twenty-one trillion, three hundred twenty-one billion, two hundred twenty million, twenty-one", and thus it is an aban number.