from math import isqrt

lim = 10**7 + 10
prime_flag = [1]*lim
prime_flag[0] = 0
prime_flag[1] = 0
ans = [-1]*lim
for p in range(2,lim):
    if p >= 3 and prime_flag[p-2]&prime_flag[p]:
        ans[p-2] = (p-2)*p
    else:
        ans[p-2] = ans[p-3]
    if prime_flag[p]:
        for q in range(2*p,lim,p):
            prime_flag[q] = 0

t = int(input())
for i in range(t):
    n = int(input())
    print(ans[isqrt(n+1)-1])