import bisect
from sympy import primerange

t = int(input())
ps = list(primerange(int(1e7)))
twin_primes = []
for i in range(len(ps)-1):
    if ps[i+1] - ps[i] == 2:
        twin_primes.append((ps[i], ps[i+1]))
twins = []
for i in twin_primes:
    twins.append(i[0]*i[1])
for i in range(t):
    n = int(input())
    if n <= 14:
        print(-1)
        continue

    idx = bisect.bisect_left(twins, n+1)
    print(twins[idx-1])