21220202121 has 4 divisors (see below), whose sum is σ = 28293602832. Its totient is φ = 14146801412.

The previous prime is 21220202083. The next prime is 21220202131. The reversal of 21220202121 is 12120202212.

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 not a de Polignac number, because 21220202121 - 2¹⁷ = 21220071049 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21220202121.

It is not an unprimeable number, because it can be changed into a prime (21220202131) 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, 3536700351 + ... + 3536700356.

It is an arithmetic number, because the mean of its divisors is an integer number (7073400708).

Almost surely, 2^21220202121 is an apocalyptic number.

It is an amenable number.

21220202121 is a deficient number, since it is larger than the sum of its proper divisors (7073400711).

21220202121 is an equidigital number, since it uses as much as digits as its factorization.

21220202121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7073400710.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21220202121 its reverse (12120202212), we get a palindrome (33340404333).

Subtracting from 21220202121 its reverse (12120202212), we obtain a palindrome (9099999909).

The spelling of 21220202121 in words is "twenty-one billion, two hundred twenty million, two hundred two thousand, one hundred twenty-one".