#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int, int> PII;
const int N = 1e6 + 10;
bool st[N];
vector <vector<int>> s(N);
set <int> q;
vector <PII> l;
void solve()
{
	int n;
    std:: cin >> n;
	for(int i = 1; i <= n; i ++ )
	{
		s[i].clear();
	}
    int cnt = 0;
	for(int i = 2; i <= n; i ++ )
	{
		if(!st[i])
		{
			cnt ++ ;
		}
		for(int j = i; j <= n; j += i)
		{
			s[i].push_back(j);
			st[j] = true;
		}
	} 
	// for(auto p : s[2])
	// {
	// 	std:: cout << p << " ";
	// }
	q.clear();
	l.clear();

	for(int i = 1; i <= n; i ++ )
	{
		q.insert(i);
	}
	for(int i = 2; i <= n; i ++ )
	{
		int ans1, ans2;
		if(st[i])
		{
			int pre1, pre2;
			for(int j = 0; j < s[i].size(); )
			{
				while(j <= s[i].size() - 1 && q.find(s[i][j]) == q.end())
				{
					j ++ ;
				}	
				pre1 = j;
				ans1 = s[i][j];

				j ++ ;
				while(j <= s[i].size() - 1 && q.find(s[i][j]) == q.end())
				{
					j ++ ;
				}
				pre2 = j;
				ans2 = s[i][j];
				j ++ ;

				if(pre1 < s[i].size() && pre2 < s[i].size())
				{
					q.erase(ans1);
					q.erase(ans2);
					l.push_back({ans1, ans2});							
				}
				
			}			
		}
		
	}

	std:: cout << l.size();
	for(auto p : l)
	{
		std:: cout << " " << p.first << " " << p.second;
	}
	std:: cout << endl;
}  
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int T;
    std:: cin >> T;
    while(T -- )
    solve();
    return 0;
}