Formater un nombre avec un séparateur (millier)

function AddThousandSeparator(S: string; Chr: char): string;
var I: integer;
begin
Result := S;
I := Length(S)-2;
while I > 1 do begin
Insert(Chr, Result, I);
I := I - 3;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
Edit1.Text := AddThousandSeparator('400500210',' ');
{ou Edit1.Text := FormatFloat('#,###,###.###', 23453452);}
end;