11111111221 has 8 divisors (see below), whose sum is σ = 12913640640. Its totient is φ = 9362388768.

The previous prime is 11111111159. The next prime is 11111111237. The reversal of 11111111221 is 12211111111.

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 11111111221 - 2¹¹ = 11111109173 is a prime.

It is a super-2 number, since 2×11111111221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111117221) 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, 13451296 + ... + 13452121.

It is an arithmetic number, because the mean of its divisors is an integer number (1614205080).

Almost surely, 2^11111111221 is an apocalyptic number.

It is an amenable number.

11111111221 is a deficient number, since it is larger than the sum of its proper divisors (1802529419).

11111111221 is an equidigital number, since it uses as much as digits as its factorization.

11111111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26903483.

The product of its digits is 4, while the sum is 13.

Adding to 11111111221 its reverse (12211111111), we get a palindrome (23322222332).

It can be divided in two parts, 1111111 and 1221, that multiplied together give a palindrome (1356666531).

The spelling of 11111111221 in words is "eleven billion, one hundred eleven million, one hundred eleven thousand, two hundred twenty-one".