The host at this IP address is obviously operated by cybercriminals. It is running a malware botnet controller which is being used to control infected computers (bots) around the globe using a trojan horse.
Malware botnet controller located at 51.81.139.72 on port 10762 TCP:
$ telnet 51.81.139.72 10762
Trying 51.81.139.72…
Connected to 51.81.139.72.
Escape character is ‘^]’
$ nslookup 51.81.139.72
ip72.ip-51-81-139.us
Referencing malware samples (MD5 hash):
9c9f8797c9be67a468c2952e5fd6ddfb — AV detection: 36 / 67 (53.73%)