Adding to 21313 its reverse (31312), we get a palindrome (52625).
Subtracting 21313 from its reverse (31312), we obtain a palindrome (9999).
21313 is nontrivially palindromic in base 12.
It is a strong prime.
It is a cyclic number.
It is a nialpdrome in base 9.
It is a self number, because there is not a number n which added to its sum of digits gives 21313.
It is a good prime.
221313 is an apocalyptic number.
It is an amenable number.
21313 is an equidigital number, since it uses as much as digits as its factorization.
21313 is an evil number, because the sum of its binary digits is even.
The square root of 21313 is about 145.9897256659. The cubic root of 21313 is about 27.7256367069.
The spelling of 21313 in words is "twenty-one thousand, three hundred thirteen".