21220321121 has 4 divisors (see below), whose sum is σ = 21220802244. Its totient is φ = 21219840000.

The previous prime is 21220321099. The next prime is 21220321123. The reversal of 21220321121 is 12112302212.

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 526060096 + 20694261025 = 22936^2 + 143855^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220321121 - 2¹⁰ = 21220320097 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 21220321121.

It is not an unprimeable number, because it can be changed into a prime (21220321123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166880 + ... + 265121.

It is an arithmetic number, because the mean of its divisors is an integer number (5305200561).

Almost surely, 2^21220321121 is an apocalyptic number.

It is an amenable number.

21220321121 is a deficient number, since it is larger than the sum of its proper divisors (481123).

21220321121 is an equidigital number, since it uses as much as digits as its factorization.

21220321121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481122.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21220321121 its reverse (12112302212), we get a palindrome (33332623333).

The spelling of 21220321121 in words is "twenty-one billion, two hundred twenty million, three hundred twenty-one thousand, one hundred twenty-one".