from bisect import bisect_left, bisect_right

def eratosthenes(n):
    sieve = [True] * (n + 1)
    for i in range(int(n**0.5) + 1):
        if i < 2:
            sieve[i] = False
        elif sieve[i]:
            for j in range(2, n//i + 1):
                sieve[i * j] = False
    ans = []
    for i in range(n+1):
        if sieve[i]:
            ans.append(i)
    return ans

E = eratosthenes(10**7)
A = []
for i in range(len(E)-1):
    l, r = E[i], E[i+1]
    if l+2 == r:
        A.append(l*r)

for _ in range(int(input())):
    N = int(input())
    b = bisect_right(A, N)
    if 1 <= b:
        print(A[b-1])
    else:
        print(-1)