from math import isqrt
from itertools import pairwise
from bisect import bisect_right


def make_primes(n: int) -> list[int]:
    ps = [2]
    t = [True] * (n + 1)
    for i in range(3, n+1, 2):
        if t[i]:
            ps.append(i)
            for j in range(i+i, n+1, i):
                t[j] = False
    return ps


primes = make_primes(isqrt(10 ** 14))
twins = []
for a, b in pairwise(primes):
    if a+2 == b:
        twins.append(a * b)


def solve():
    N = int(input())
    p = bisect_right(twins, N)
    if p == 0: return -1

    return twins[p-1]


T = int(input())
for _ in range(T):
    ans = solve()
    print(ans)