21201122010221 has 4 divisors (see below), whose sum is σ = 21228981566844. Its totient is φ = 21173262453600.

The previous prime is 21201122010199. The next prime is 21201122010281. The reversal of 21201122010221 is 12201022110212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9149046018121 + 12052075992100 = 3024739^2 + 3471610^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201122010221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201122010221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201122010281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13929777170 + ... + 13929778691.

It is an arithmetic number, because the mean of its divisors is an integer number (5307245391711).

Almost surely, 2^{21201122010221} is an apocalyptic number.

It is an amenable number.

21201122010221 is a deficient number, since it is larger than the sum of its proper divisors (27859556623).

21201122010221 is an equidigital number, since it uses as much as digits as its factorization.

21201122010221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27859556622.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21201122010221 its reverse (12201022110212), we get a palindrome (33402144120433).

Subtracting from 21201122010221 its reverse (12201022110212), we obtain a palindrome (9000099900009).

The spelling of 21201122010221 in words is "twenty-one trillion, two hundred one billion, one hundred twenty-two million, ten thousand, two hundred twenty-one".