21201022210021 has 2 divisors, whose sum is σ = 21201022210022. Its totient is φ = 21201022210020.

The previous prime is 21201022210019. The next prime is 21201022210031. The reversal of 21201022210021 is 12001222010212.

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., 16705939544100 + 4495082665921 = 4087290^2 + 2120161^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201022210021 - 2¹ = 21201022210019 is a prime.

Together with 21201022210019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21201022209977 and 21201022210004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201022210031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600511105010 + 10600511105011.

It is an arithmetic number, because the mean of its divisors is an integer number (10600511105011).

Almost surely, 2^{21201022210021} is an apocalyptic number.

It is an amenable number.

21201022210021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201022210021 is an equidigital number, since it uses as much as digits as its factorization.

21201022210021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21201022210021 its reverse (12001222010212), we get a palindrome (33202244220233).

The spelling of 21201022210021 in words is "twenty-one trillion, two hundred one billion, twenty-two million, two hundred ten thousand, twenty-one".