java – Prime numbers that are also a prime numbers when reversed

This is a challenge on Codewars I took years ago. Task is to find all prime numbers that are also a prime number when reversed, i.e. 13 -> 31 is such a number.
This is still the answer with the most upvotes in the categories ‘Best practice’ as well as in ‘Clever’. Know looking at this answer years later I found in the comments that I probably should have used Long.parseLong() instead of Integer.parseInt(), with which I agree. Any other improvements or thoughts about this piece of code? Please keep in mind in code challenges like this I always try to code as concise as possible.

public class BackWardsPrime {

    public static String backwardsPrime(long start, long end) {
        StringBuilder sb = new StringBuilder();
        while(start <= end){
            int rev = Integer.parseInt(new StringBuilder(
            String.valueOf(start)).reverse().toString());
            if(start > 12 && isPrime(rev) && isPrime(start) && start != rev) 
                sb.append(start + " ");  
            start++;
        }
        return sb.toString().trim();
    }
    
    static boolean isPrime(long n) {
        if(n % 2 == 0) return false;
        for(int i = 3; i * i  <= n  ; i += 2) {
            if(n % i == 0)
                return false;
        }
        return true;
    }
}