from more_itertools import *
from bisect import *
sosu = list(sieve(10000000+100))
tmp = [-1]
for i in range(1,len(sosu)):
    if sosu[i]-2 == sosu[i-1]:
        tmp.append(sosu[i]*sosu[i-1])

T = int(input())

for i in range(T):
    N = int(input())
    print(tmp[bisect_right(tmp,N)-1])