21210012016021 has 2 divisors, whose sum is σ = 21210012016022. Its totient is φ = 21210012016020.

The previous prime is 21210012016019. The next prime is 21210012016073. The reversal of 21210012016021 is 12061021001212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13054932411921 + 8155079604100 = 3613161^2 + 2855710^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210012016021 - 2¹ = 21210012016019 is a prime.

It is a super-3 number, since 3×21210012016021³ (a number of 41 digits) contains 333 as substring.

Together with 21210012016019, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21210012016021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210012016091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605006008010 + 10605006008011.

It is an arithmetic number, because the mean of its divisors is an integer number (10605006008011).

Almost surely, 2^{21210012016021} is an apocalyptic number.

It is an amenable number.

21210012016021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210012016021 is an equidigital number, since it uses as much as digits as its factorization.

21210012016021 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 19.

Adding to 21210012016021 its reverse (12061021001212), we get a palindrome (33271033017233).

The spelling of 21210012016021 in words is "twenty-one trillion, two hundred ten billion, twelve million, sixteen thousand, twenty-one".