#include <bits/stdc++.h>
using namespace std;
const long long maxn = 100005;
const long long inf = 0x3f3f3f3f;
const long long mod = 1e9 + 7;
long long n, m, k;
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
long long a[] = {
    1286328,     5152048,     11602684,    20625536,    32233220,
    46424584,    63184780,    82524348,    104468352,   128964060,
    156043372,   185723012,   217960740,   252768352,   290187924,
    330152808,   372710892,   417898044,   465586236,   515896608,
    568822244,   624232172,   682249076,   742926152,   806078872,
    871878320,   940286700,   1011192488,  1084684700,  1160827392,
    1239471484,  1320724372,  1404629744,  1490985868,  1579992584,
    1671629048,  1765719876,  1862466656,  1961853036,  2063686776,
    2168119952,  2275302316,  2384801992,  2497055000,  2611926012,
    2729210680,  2849202512,  2971799760,  3096857344,  3224493616,
    3354885356,  3487671904,  3623054852,  3761218212,  3901742568,
    4044888408,  4190687836,  4338934252,  4489837672,  4643432832,
    4799434868,  4958077452,  5119485960,  5283125660,  5449527516,
    5618574280,  5790030072,  5964129996,  6140934952,  6320176760,
    6501931956,  6686611528,  6873508032,  7063091948,  7255393156,
    7450141992,  7647451552,  7847463468,  8049742432,  8254864212,
    8462723928,  8672822172,  8885709144,  9101312360,  9319022312,
    9539592028,  9762887036,  9988526040,  10216758772, 10447886764,
    10681198964, 10917098160, 11155866368, 11397049444, 11640716016,
    11887311388, 12136034512, 12387633740, 12641894356, 12898363344};
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  m = n / 1000;
  k = n % 1000;
  long long ans = a[m - 1];
  for (long long i = m * 1000 + 1; i <= n; i++) {
    for (long long j = 2; j <= i / 2; j++) {
      if (i % j == 0) {
        ans += 4 * (i / j);
      }
    }
  }
  cout << ans << "\n";
}
