Prime Palindrome

This is one tough medium problem and I had to look at the official solution to solve this. I can solve for smaller numbers but once it gets to 7+ digits then I always get the Time Limit Exceeded result.

class Solution {
    fun isPrime(num: Int): Boolean { 
        if(num < 2) return false
        return !(2..Math.sqrt(num.toDouble()).toInt()).any { num % it == 0 }        
    }
    
    fun reverse(num: Int): Int {
        var a = 0
        var n = num
        while(n > 0){
            a = 10 * a + n % 10
            n = n / 10
        }
        
        return a
    }
    
    fun primePalindrome(N: Int): Int {
        var n = N
        while(true){
            if(n == reverse(n) && isPrime(n)) return n
            n++
                
            if(n > 10000000 && n < 100000000){
                n = 100000000
            }
        }
        
        return 0
    }
}
Runtime: 160 ms, faster than 100.00% of Kotlin online submissions for Prime Palindrome.
Memory Usage: 31.3 MB, less than 100.00% of Kotlin online submissions for Prime Palindrome.
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