import bisect
import sys
from math import isqrt
from typing import List, Tuple

sys.setrecursionlimit(10 ** 6)

MOD = 998244353

int1 = lambda x: int(x) - 1
input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    mx = 10 ** 7 + 1
    arr = [15]
    p = [True] * (mx + 1)
    p[0] = p[1] = False
    for i in range(2, isqrt(mx) + 1):
        if not p[i]: continue
        for j in range(i * i, mx + 1, i):
            p[j] = False

    for i in range(5, mx - 1, 6):
        if p[i] and p[i + 2]:
            arr.append(i * (i + 2))

    t = ii()
    for _ in range(t):
        n = ii()
        idx = bisect.bisect_right(arr, n)
        print(-1 if idx == 0 else arr[idx - 1])


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()