use integer division, avoiding unnecessary object creation and method calls:

public class MillisecondsToDays {
    public static void main(String[] args) {
        long milliseconds = 172800000L; // Example: 2 days in milliseconds
        long days = milliseconds / (24 * 60 * 60 * 1000);
        System.out.println("Days: " + days);
    }
}

Why is this the best solution?

1. Performance Optimized: Uses simple arithmetic operations (multiplication and division), which are the fastest.
2. No Unnecessary Objects: Doesn't involve unnecessary Date, Calendar, or TimeUnit classes.
3. Integer Division: Since milliseconds are in long, this ensures precise calculation without floating-point inaccuracies.