11111111212221 has 24 divisors (see below), whose sum is σ = 17350684185120. Its totient is φ = 6827880570336.

The previous prime is 11111111212217. The next prime is 11111111212237. The reversal of 11111111212221 is 12221211111111.

11111111212221 is a `hidden beast` number, since 11 + 111 + 111 + 212 + 221 = 666.

11111111212221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11111111212221 - 2² = 11111111212217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 11111111212194 and 11111111212203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111111212241) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 878064735 + ... + 878077388.

It is an arithmetic number, because the mean of its divisors is an integer number (722945174380).

Almost surely, 2^{11111111212221} is an apocalyptic number.

It is an amenable number.

11111111212221 is a deficient number, since it is larger than the sum of its proper divisors (6239572972899).

11111111212221 is a wasteful number, since it uses less digits than its factorization.

11111111212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1756142185 (or 1756142182 counting only the distinct ones).

The product of its digits is 16, while the sum is 18.

Adding to 11111111212221 its reverse (12221211111111), we get a palindrome (23332322323332).

The spelling of 11111111212221 in words is "eleven trillion, one hundred eleven billion, one hundred eleven million, two hundred twelve thousand, two hundred twenty-one".