An easier way to write this SQL

We have a table containing an Employee ID in the format 'E00000001'. It is monotonically incremented. I want to write a SQL statement to get the next available number .e.g 'E00000002'. We can't use a sequence for reasons I won't bore you with. The following works, but is there a more elegant way to write it?

SELECT 'E' || LPAD(MAX(TO_NUMBER(SUBSTR(EXTERNAL_ID,2,9))+1),9,'0') FROM EXTID Received on Wed Jul 28 1999 - 22:19:07 CDT