The IP address 172.16.81.255 : Class B networks
Secure IP address This IP is only local, it is not accessible from outside the network
Rating: 5
This means that the IP address is not accessible from the Internet, it is local and only accessible within the network. Everyone has the same local address (172.16.0.0 - 172.31.255.255).
Each device (laptop, printer, scanner, phone, surveillance camera, tablet, ...) has a unique local IP address assigned by the adsl box that allows the box to identify the different devices to within a local network and send the right product at the right flow.
Specifically, the adsl box has a public IP address in your case, which connects to the Internet and the box assigns a local address to all devices to identify them.
The IP address 172.16.81.255 detail
The IP address 172.16.81.255 (IPv4 Class B networks) belonging to the network 172.16.0.0 - 172.31.255.255 is written in long version -1408216577.
Color obtained mathematically from the IP address: Purplish red
Addresses on the same network : 172.16.81.0 172.16.81.1 172.16.81.2 172.16.81.3 172.16.81.4 172.16.81.5 172.16.81.6 172.16.81.7 172.16.81.8 172.16.81.9 172.16.81.10 172.16.81.20 172.16.81.30 172.16.81.40 172.16.81.50 172.16.81.60 172.16.81.70 172.16.81.80 172.16.81.90 172.16.81.100 172.16.81.200 172.16.81.254