Need Formula to convert Minutes into hh:mm:ss

Ok .. here is the problem . . .
I have a spot on my spreadsheet where I am given an ammount of time in minutes.
I need to convert it to hours:minutes:seconds (ie: hh:mm:ss)
Can anyone help??

Example:
6214.11 must be converted to 103:43:12
In other words:
6214.11 minutes becomes 103hours, 43mins, 12 seconds

Can be done either one of 2 ways ...
Dont care which as long as it works.

Either:
A3=PRODUCT(A1,A2)
B1=(formula here converting answer from A3 to hh:mm:ss)
OR
use the current
A3=PRODUCT(A1,A2)
and somehow change the number format to show it the way i need it to.
(none of the preset number formats works unless you have a custom one i can use)