IRC was originally a plain text protocol (although later extended), which on request was assigned port 194/TCP by IANA. However, the de facto standard has always been to run IRC on 6667/TCP and nearby port numbers (for example TCP ports 6660–6669, 7000) to avoid having to run the IRCd software with root privileges.
Default ports: 194, 6667
PORT STATE SERVICE6667/tcp open irc
nmap -sV --script irc-botnet-channels,irc-info,irc-unrealircd-backdoor -p 194,6660-7000 irked.htb