MySQL Replication: Seconds Behind Master super high
When you see the Seconds_Behind_Master that high, I look at the following:

Relay_Log_Space: 8179978166


You have  7.6182GB of relay logs to process.

Master_Log_File: mysql-bin.000173
Relay_Master_Log_File: mysql-bin.000093


This tell me that you have read up to mysql-bin.000173, but you are currently processing things from the mysql-bin.000093.

This also tell me you have about 80 binary logs on the Master, each about 100 MB.

The Seconds_Behind_Master is simply the NOW() minus the TIMESTAMP set at mysql-bin.000093 (Relay_Master_Log_File) position 91173210 (Exec_Master_Log_Pos).

As long as Slave_SQL_Thread is Yes, the relay logs get processed


Relay_Log_Space will decrease each time a relay log is done
Exec_Master_Log_Pos will increase until current relay log is done, then resets to the beginning of the next relay
TIMESTAMP keeps increasing, which make Seconds_Behind_Master decrease (NOW() minus the TIMESTAMP set at Relay_Master_Log_File position Exec_Master_Log_Pos)


This is what happens when replication is off for 486330 seconds (5 days 15 hours 5 minutes 29 seconds) and you run start slave;

Look at your SHOW PROCESSLIST;. The IO Thread has been up for 66530 seconds (18 hours 28 minutes 50 seconds). This means someone or something started replication 18 hours 28 minutes 50 seconds ago.

You stated in your question that you have set up replication for the production server. This means that you ran the mysqldump 5 days 15 hours 5 minutes 29 seconds ago and started replicating from the production master 18 hours 28 minutes 50 seconds ago.

If you had setup the Slave the same day you got the mysqldump from the Master the replication load would be a lot less. Notwithstanding, replication is working normally provided Slave_IO_Thread and Slave_SQL_Thread both say Yes.