
theorem
  2017 is prime
proof
  now
    2017 = 2*1008 + 1; hence not 2 divides 2017 by NAT_4:9;
    2017 = 3*672 + 1; hence not 3 divides 2017 by NAT_4:9;
    2017 = 5*403 + 2; hence not 5 divides 2017 by NAT_4:9;
    2017 = 7*288 + 1; hence not 7 divides 2017 by NAT_4:9;
    2017 = 11*183 + 4; hence not 11 divides 2017 by NAT_4:9;
    2017 = 13*155 + 2; hence not 13 divides 2017 by NAT_4:9;
    2017 = 17*118 + 11; hence not 17 divides 2017 by NAT_4:9;
    2017 = 19*106 + 3; hence not 19 divides 2017 by NAT_4:9;
    2017 = 23*87 + 16; hence not 23 divides 2017 by NAT_4:9;
    2017 = 29*69 + 16; hence not 29 divides 2017 by NAT_4:9;
    2017 = 31*65 + 2; hence not 31 divides 2017 by NAT_4:9;
    2017 = 37*54 + 19; hence not 37 divides 2017 by NAT_4:9;
    2017 = 41*49 + 8; hence not 41 divides 2017 by NAT_4:9;
    2017 = 43*46 + 39; hence not 43 divides 2017 by NAT_4:9;
  end;
  then for n being Element of NAT st 1 < n & n*n <= 2017 & n is prime
  holds not n divides 2017 by XPRIMET1:28;
  hence thesis by NAT_4:14;
end;
