21212201221121 has 8 divisors (see below), whose sum is σ = 21234902759304. Its totient is φ = 21189508070400.

The previous prime is 21212201221111. The next prime is 21212201221187. The reversal of 21212201221121 is 12112210221212.

It can be written as a sum of positive squares in 4 ways, for example, as 1006600857025 + 20205600364096 = 1003295^2 + 4495064^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212201221121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212201221093 and 21212201221102.

It is not an unprimeable number, because it can be changed into a prime (21212201221111) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2970461 + ... + 7158773.

It is an arithmetic number, because the mean of its divisors is an integer number (2654362844913).

Almost surely, 2^{21212201221121} is an apocalyptic number.

It is an amenable number.

21212201221121 is a deficient number, since it is larger than the sum of its proper divisors (22701538183).

21212201221121 is a wasteful number, since it uses less digits than its factorization.

21212201221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4193731.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21212201221121 its reverse (12112210221212), we get a palindrome (33324411442333).

Subtracting from 21212201221121 its reverse (12112210221212), we obtain a palindrome (9099990999909).

The spelling of 21212201221121 in words is "twenty-one trillion, two hundred twelve billion, two hundred one million, two hundred twenty-one thousand, one hundred twenty-one".