21210202002221 has 4 divisors (see below), whose sum is σ = 21258516813600. Its totient is φ = 21161887190844.

The previous prime is 21210202002169. The next prime is 21210202002247. The reversal of 21210202002221 is 12220020201212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210202002221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21210202002221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210202002251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24157405031 + ... + 24157405908.

It is an arithmetic number, because the mean of its divisors is an integer number (5314629203400).

Almost surely, 2^{21210202002221} is an apocalyptic number.

It is an amenable number.

21210202002221 is a deficient number, since it is larger than the sum of its proper divisors (48314811379).

21210202002221 is an equidigital number, since it uses as much as digits as its factorization.

21210202002221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48314811378.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21210202002221 its reverse (12220020201212), we get a palindrome (33430222203433).

The spelling of 21210202002221 in words is "twenty-one trillion, two hundred ten billion, two hundred two million, two thousand, two hundred twenty-one".