11111001221 has 4 divisors (see below), whose sum is σ = 11293148844. Its totient is φ = 10928853600.

The previous prime is 11111001191. The next prime is 11111001227. The reversal of 11111001221 is 12210011111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12210011111 = 569 ⋅21458719.

It can be written as a sum of positive squares in 2 ways, for example, as 755700100 + 10355301121 = 27490^2 + 101761^2 .

It is a cyclic number.

It is not a de Polignac number, because 11111001221 - 2²² = 11106806917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111001227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91073720 + ... + 91073841.

It is an arithmetic number, because the mean of its divisors is an integer number (2823287211).

Almost surely, 2^11111001221 is an apocalyptic number.

It is an amenable number.

11111001221 is a deficient number, since it is larger than the sum of its proper divisors (182147623).

11111001221 is an equidigital number, since it uses as much as digits as its factorization.

11111001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182147622.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 11111001221 its reverse (12210011111), we get a palindrome (23321012332).

The spelling of 11111001221 in words is "eleven billion, one hundred eleven million, one thousand, two hundred twenty-one".