/* -*- coding: utf-8 -*-
 *
 * 3296.cc:  No.3296 81-like number - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_P = 100000 + 50;

/* typedef */

using ll = long long;
using vb = vector<bool>;
using vi = vector<int>;

/* global variables */

vb primes;
vi pnums;

/* subroutines */

int gen_primes(int maxp) {
  primes.assign(maxp + 1, true);
  primes[0] = primes[1] = false;

  int p;
  for (p = 2; p * p <= maxp; p++)
    if (primes[p]) {
      pnums.push_back(p);
      for (int q = p * p; q <= maxp; q += p) primes[q] = false;
    }
  for (; p <= maxp; p++)
    if (primes[p]) pnums.push_back(p);
  return (int)pnums.size();
}

ll powi(ll a, int e) {
  ll p = 1;
  while (e > 0) {
    if (e & 1) p *= a;
    a *= a;
    e >>= 1;
  }
  return p;
}

/* main */

int main() {
  gen_primes(MAX_P);
  
  ll n;
  scanf("%lld", &n);

  ll sum = 0;
  for (auto p: pnums) {
    if ((ll)p * p > n) break;

    int e = 0;
    for (ll m = n; m >= p; e++, m /= p);

    sum += (powi(p, e - 1) - 1) / (p - 1) * p * p;
  }

  printf("%lld\n", sum);
  
  return 0;
}