21211211221 has 8 divisors (see below), whose sum is σ = 21248136000. Its totient is φ = 21174315840.

The previous prime is 21211211213. The next prime is 21211211227. The reversal of 21211211221 is 12211211212.

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

It is a cyclic number.

It is not a de Polignac number, because 21211211221 - 2³ = 21211211213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211211195 and 21211211204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211211227) 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 7 ways as a sum of consecutive naturals, for example, 1807230 + ... + 1818928.

It is an arithmetic number, because the mean of its divisors is an integer number (2656017000).

Almost surely, 2^21211211221 is an apocalyptic number.

It is an amenable number.

21211211221 is a deficient number, since it is larger than the sum of its proper divisors (36924779).

21211211221 is a wasteful number, since it uses less digits than its factorization.

21211211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14699.

The product of its digits is 32, while the sum is 16.

Adding to 21211211221 its reverse (12211211212), we get a palindrome (33422422433).

Subtracting from 21211211221 its reverse (12211211212), we obtain a palindrome (9000000009).

The spelling of 21211211221 in words is "twenty-one billion, two hundred eleven million, two hundred eleven thousand, two hundred twenty-one".