11111121221 has 16 divisors (see below), whose sum is σ = 11640754944. Its totient is φ = 10585474944.

The previous prime is 11111121211. The next prime is 11111121247. The reversal of 11111121221 is 12212111111.

It is a cyclic number.

It is not a de Polignac number, because 11111121221 - 2¹⁰ = 11111120197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11111121196 and 11111121205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111121211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9313001 + ... + 9314193.

It is an arithmetic number, because the mean of its divisors is an integer number (727547184).

Almost surely, 2^11111121221 is an apocalyptic number.

It is an amenable number.

11111121221 is a deficient number, since it is larger than the sum of its proper divisors (529633723).

11111121221 is a wasteful number, since it uses less digits than its factorization.

11111121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2500.

The product of its digits is 8, while the sum is 14.

Adding to 11111121221 its reverse (12212111111), we get a palindrome (23323232332).

The spelling of 11111121221 in words is "eleven billion, one hundred eleven million, one hundred twenty-one thousand, two hundred twenty-one".