In this section I am going to share a small tip that will help you to know which port occupied by which program.
netstat -ab | findstr 35729
It will tell you which program is being used by this port. If output nothing then the port is being unused.
For listing all port services running type below code inside your command prompt.
Go to a command prompt and run
netstat -a -n -p tcp -b NETSTAT -p tcp -ano netstat -p tcp -ano | findstr :21
This will show all services running, protocal used, local and foreign address, state and PID (process identifier).