Adding to 21313220311231 its reverse (13211302231312), we get a palindrome (34524522542543).
It is a strong prime.
It is a cyclic number.
It is a congruent number.
Almost surely, 221313220311231 is an apocalyptic number.
21313220311231 is an equidigital number, since it uses as much as digits as its factorization.
21313220311231 is an evil number, because the sum of its binary digits is even.
The spelling of 21313220311231 in words is "twenty-one trillion, three hundred thirteen billion, two hundred twenty million, three hundred eleven thousand, two hundred thirty-one".