21202321121 has 4 divisors (see below), whose sum is σ = 21202615044. Its totient is φ = 21202027200.

The previous prime is 21202321099. The next prime is 21202321123. The reversal of 21202321121 is 12112320212.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11590675600 + 9611645521 = 107660^2 + 98039^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21202321121 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 21202321121.

It is not an unprimeable number, because it can be changed into a prime (21202321123) 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, 43661 + ... + 210501.

It is an arithmetic number, because the mean of its divisors is an integer number (5300653761).

Almost surely, 2^21202321121 is an apocalyptic number.

It is an amenable number.

21202321121 is a deficient number, since it is larger than the sum of its proper divisors (293923).

21202321121 is a wasteful number, since it uses less digits than its factorization.

21202321121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293922.

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

Adding to 21202321121 its reverse (12112320212), we get a palindrome (33314641333).

Subtracting from 21202321121 its reverse (12112320212), we obtain a palindrome (9090000909).

The spelling of 21202321121 in words is "twenty-one billion, two hundred two million, three hundred twenty-one thousand, one hundred twenty-one".