It is a happy number.
It is a cyclic number.
It is a Duffinian number.
It is a congruent number.
Almost surely, 211111221202221 is an apocalyptic number.
It is an amenable number.
11111221202221 is a wasteful number, since it uses less digits than its factorization.
11111221202221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 4430304.
Adding to 11111221202221 its reverse (12220212211111), we get a palindrome (23331433413332).
The spelling of 11111221202221 in words is "eleven trillion, one hundred eleven billion, two hundred twenty-one million, two hundred two thousand, two hundred twenty-one".