You can display a number as time (with a time format) by using "&/" followed by a digit. Time is determined by calculating the number of seconds since midnight that the value represents. The digit in the format corresponds to the order in which the time format appears in the Format drop-down menu.
...corresponds to the 5th time format in the pop-up menu, specifically the AM/PM time. A number field with this format would display 25000 as: