How to convert Integer value to string without library function in c#

31:33

09:56

1:23:02

2:12:57

1:34:36

07:53

24:57

23:36

2:18:23

1:06:42

13:56

11:43

16:32

03:12

1:18:59

12:19

07:27

30:50

15:46

19:00