Constraint error overflow

[Richard Iswara <haujekchifan@gmail.com>]

Ada beginner here. I was trying to multiply the first 100 integer and GNAT throw me a constraint error, overflow. I check the error was on integer 13. So what did I do wrong here?
Gnat CE 2020, Windows 10 Pro 64bit.
Here is the relevant program:

with Ada.Text_IO;
with Ada.Integer_Text_IO;

procedure Simple is
   sum : Natural := 0;
   mul : Natural := 1;

begin
   Ada.Text_IO.Put ( "Sum of first 100 integer is :" );
   Summing:
   for I in 1 .. 100 loop
      sum := sum + I;
   end loop Summing;
   Ada.Integer_Text_IO.Put ( sum );
   Ada.Text_IO.New_Line;

   Ada.Text_IO.Put ( "Multiple of the first 100 integer is :" );
   Ada.Text_IO.New_Line;
   Multiplying:
   for J in 1 .. 100 loop
      Ada.Integer_Text_IO.Put (J);
      Ada.Text_IO.New_Line;
      mul := mul * J;
   end loop Multiplying;
   Ada.Integer_Text_IO.Put ( mul );
   Ada.Text_IO.New_Line;
end Simple;