111111111221 has 16 divisors (see below), whose sum is σ = 123295411008. Its totient is φ = 99286387200.

The previous prime is 111111111187. The next prime is 111111111253. The reversal of 111111111221 is 122111111111.

It is not a de Polignac number, because 111111111221 - 2¹⁴ = 111111094837 is a prime.

It is a super-2 number, since 2×111111111221² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 111111111196 and 111111111205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111111111271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 129020 + ... + 488741.

It is an arithmetic number, because the mean of its divisors is an integer number (7705963188).

Almost surely, 2^111111111221 is an apocalyptic number.

111111111221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

111111111221 is a deficient number, since it is larger than the sum of its proper divisors (12184299787).

111111111221 is a wasteful number, since it uses less digits than its factorization.

111111111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618052.

The product of its digits is 4, while the sum is 14.

Adding to 111111111221 its reverse (122111111111), we get a palindrome (233222222332).

It can be divided in two parts, 11111111 and 1221, that multiplied together give a palindrome (13566666531).

The spelling of 111111111221 in words is "one hundred eleven billion, one hundred eleven million, one hundred eleven thousand, two hundred twenty-one".