That's not quite how tail numbers work in the US. They are like license plates, with custom numbers only available on request and they must follow a specific format. Airlines may try to get tail numbers that follow some arbitrary preference, but it's just as feasible for an antique Piper Cub to have that number instead. Some private owners change numbers just to have one that is easier to say over the radio or has personal meaning, like an anniversary date or initials. There may be no more than 5 characters after the N, with at least the first being a number and only the last two having the option of being letters, e.g. N1, N12345, N1A, N123AZ, with letters I and O not allowed.