I was trying to remember the port number of my Oracle Rac in Oracle Linux.
Then, I find this information in $ORACLE_HOME/install/portlist.ini.
In this case the port number was 1158 (the default number), but it is important you know about this file because it can help you in other situation.
Also you can find this information in $ORACLE_HOME/Oracle_sid/sysman/config/emd.properties by variable REPOSITORY_URL:
I hope this post can help you.
More informations in : Oracle® Database 2 Day DBA 11g Release 2 (11.2) Part Number E10897-06