l=10**7
P=[1]*l
P[0]=0
P[1]=0
for i in range(2,l):
  if P[i]:
    for j in range(i+i,l,i):
      P[j]=0
P=[i for i in range(2,l) if P[i]]
pp=[P[i]*P[i+1] for i in range(len(P)-1) if P[i]+2==P[i+1]]
from bisect import bisect_right
T=int(input())
for _ in range(T):
  n=int(input())
  p=bisect_right(pp,n)
  print(pp[p-1] if p>0 else -1)