Here 1502483083 specifies the DBID and 20110416 specifies the date i.e, 16th april 2011
2.) If we have any text files that preserve the output from an RMAN session, the DBID is displayed by the RMAN client when it starts up and connects to your database. Typical output follows:
C:\>rman target sys/xxxx@noida
Recovery Manager: Release 220.127.116.11.0 - Production on Sat Apr 16 17:23:28 2011
Copyright (c) 1982, 2007, Oracle. All rights reserved.
connected to target database: NOIDA (DBID=1502483083)
Enjoy J J J