This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The first thing is to figure out what the number means for your database. Is it milliseconds since January 1st, 1970 or something else.
At that point, I would write a program to load the number into a java.util.Date object and output it. (You could do this with a calculator if you had to, but I can't imagine why you want to do that. Accounting for leap years and the like would be a nuisance.)
If you were using JDBC to get the SQL TIME, you could call rs.getTimeStamp and output that directly.