11211221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a Duffinian number.
It is a congruent number.
Almost surely, 211211221 is an apocalyptic number.
It is an amenable number.
11211221 is an equidigital number, since it uses as much as digits as its factorization.
11211221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3091.
The square root of 11211221 is about 3348.3161439745. The cubic root of 11211221 is about 223.8124825760.
Adding to 11211221 its reverse (12211211), we get a palindrome (23422432).
The spelling of 11211221 in words is "eleven million, two hundred eleven thousand, two hundred twenty-one".