from bisect import bisect_right


def get_primes(size=10**7):
    global is_prime
    is_prime = [True] * (size + 1)
    is_prime[0] = is_prime[1] = False
    primes = []
    for i in range(size + 1):
        if not is_prime[i]:
            continue
        primes.append(i)
        j = 2
        while i * j <= size:
            is_prime[i * j] = False
            j += 1
    return primes

primes = get_primes()
ps = []
for p in primes[:-1]:
    if is_prime[p + 2]:
        ps.append(p * (p + 2))

T = int(input())
for _ in range(T):
    N = int(input())
    idx = bisect_right(ps, N) - 1
    if idx >= 0:
        print(ps[idx])
    else:
        print(-1)