alter FUNCTION dbo.ToDateTime2 ( @Ticks bigint )
  RETURNS datetime2
AS
BEGIN
    DECLARE @DateTime datetime2 = '16000102';
    SET @DateTime = DATEADD( DAY, @Ticks / 864000000000, @DateTime );
    SET @DateTime = DATEADD( SECOND, ( @Ticks % 864000000000) / 10000000, @DateTime );
    RETURN DATEADD( NANOSECOND, ( @Ticks % 10000000 ) * 100, @DateTime );
END

select dbo.ToDateTime2 (132730705745833389)

---------------------------
2020-08-10 12:02:54.5833389

(1 row affected)