Adding to 21230221 its reverse (12203212), we get a palindrome (33433433).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is a cyclic number.
It is a Duffinian number.
It is a congruent number.
Almost surely, 221230221 is an apocalyptic number.
It is an amenable number.
21230221 is an equidigital number, since it uses as much as digits as its factorization.
21230221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 11570.
The square root of 21230221 is about 4607.6263954448. The cubic root of 21230221 is about 276.8969497687.
The spelling of 21230221 in words is "twenty-one million, two hundred thirty thousand, two hundred twenty-one".