n is a valid port number. The default is 51773.
DefaultPort is the port number for the InterSystems IRIS superserver. The superserver listens on a specified port (51773 by default) for incoming connections to InterSystems IRIS and dispatches them to the appropriate subsystem.
A standard InterSystems IRIS installation sets the superserver port number to 51773, or if that port is in use by another InterSystems IRIS instance on the same system, the next unused port number.
Changing This Parameter
On the Memory and Startup page of the Management Portal (System Administration > Configuration > System Configuration > Memory and Startup), enter a number in the Superserver Port Number field.
Instead of using the Management Portal, you can change DefaultPort in the Config.StartupOpens in a new window class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).