11111011111221 has 16 divisors (see below), whose sum is σ = 16945774460928. Its totient is φ = 6343632990000.

The previous prime is 11111011111217. The next prime is 11111011111247. The reversal of 11111011111221 is 12211111011111.

It is a happy number.

It is not a de Polignac number, because 11111011111221 - 2² = 11111011111217 is a prime.

It is a super-2 number, since 2×11111011111221² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 11111011111221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11111011112221) 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, 229817605 + ... + 229865946.

It is an arithmetic number, because the mean of its divisors is an integer number (1059110903808).

Almost surely, 2^{11111011111221} is an apocalyptic number.

It is an amenable number.

11111011111221 is a deficient number, since it is larger than the sum of its proper divisors (5834763349707).

11111011111221 is a wasteful number, since it uses less digits than its factorization.

11111011111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459684712.

The product of its (nonzero) digits is 4, while the sum is 15.

Adding to 11111011111221 its reverse (12211111011111), we get a palindrome (23322122122332).

It can be divided in two parts, 1111101 and 1111221, that multiplied together give a palindrome (1234678764321).

The spelling of 11111011111221 in words is "eleven trillion, one hundred eleven billion, eleven million, one hundred eleven thousand, two hundred twenty-one".