What could possibly cause a numeric overflow when enqueuing an Oracle AQ message?
Turns out this problem has nothing to do with message properties, and perhaps not even with the messages themselves. The cause here is actually a bug in Oracle, which you hit when the value of

select max(greatest(object_id, data_object_id)) from dba_objects;


reaches 2^31. There is actually a corresponding patch available from Oracle:

Patch 14837395: AQ CALLS FAIL WITH NUMERIC OVERFLOW WHEN DB OBJECT NUMBERS GREATER THAN 2^31