#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define Sz(x) (int)(x).size()
#define bit(x) (1ll << (x))
using ll = long long;
using db = double;
using ull = unsigned long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vii = vector<vi>;
using vl = vector<ll>;
using vll = vector<vl>;
using vs = vector<string>;
using vd = vector<db>;
mt19937 mrand(time(0));

vector<int> p, pr;
int tot;

void sieve(int n) {
    p.assign(n + 1, 0);
    pr.clear();
    
    for (int i = 2; i <= n; i++) {
        if (!p[i]) p[i] = i, pr.push_back(i);
        for (auto v : pr) {
            if (i * v > n) break;
            p[i * v] = v;
            if (v == p[i]) break;
        }
    }
    tot = (int)pr.size();
}


void solve(void)
{
	int n;
	cin >> n;
	sieve(n);
	vi vis(n + 2);
	vector<array<int, 2>> ans;
	reverse(all(pr));

	auto match = [&](int x, int y)
	{
		vis[x] = vis[y] = 1;
		ans.pb({x, y});
	};

	for (auto d : pr)
	{
		int p = 0;
		vi v;
		for (int i = d; i <= n; i += d)
			if (!vis[i])
				v.pb(i);

		for (auto i : v)
			if (!(i == d * 2 && Sz(v) & 1))
			{
				if (p)
				{
					match(i, p);
					p = 0;
				}
				else
					p = i;
			}
	}


	int m = Sz(ans);
	cout << m << " \n"[m == 0];
	for (int i = 0; i < m; i++)
		cout << ans[i][0] << " " << ans[i][1] << " \n"[i == m - 1];
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	// cout << fixed << setprecision(10);

	int T = 1;
	cin >> T;
	for (int i = 1; i <= T; i++)
	solve();

	return 0;
}