28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

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import java.util.*;
import java.io.*;
import java.math.*;
/*
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(br.readLine());
Integer.parseInt(st.nextToken());
Long.parseLong(st.nextToken());
Scanner sc = new Scanner(System.in);


*/

public class Waw{
    
    public static long countDivisors(int n){
        long nb = 0;
        for(int i=2;i<=Math.sqrt(n);i++){
            if(n%i==0){
                if(n/i==i) nb += (long) (i*4);
                else{
                    nb += (long) (i*4);
                    nb += (long) ((n/i)*4);
                }
            }
        }
        
        return nb;
    }
    
    public static void main(String[] args){
        
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long nb = 0;
        for(int i=n;i>=2;i--){
            nb += countDivisors(i);
        }
        
        System.out.println(nb);
        
        
    
    }
}