A Pokémon Trainer's ID number is a five-digit number that is assigned to a Trainer when they begin their Pokémon journey. It is used, in conjunction with the Trainer's name and gender, to identify whether the Pokémon is an outsider Pokémon by the games. The highest possible ID number in any game is 65535.
There is no way to tell what is going to be your ID or what determines it, simply ramdom.
So if you want a specific ID, it will be 1/65535.
Hope this helps.