plug "ipv6 calc" into your favorite search engine. Using your example and the first four sequentially, I got:
http://www.ipv6calculator.net
2401:4900:2180:0001::/64
Network range |
2401:4900:2180:0001:0000:0000:0000:0000 - |
|
2401:4900:2180:0001:ffff:ffff:ffff:ffff |
2401:4900:2180:0002::/64
Network range |
2401:4900:2180:0002:0000:0000:0000:0000 - |
|
2401:4900:2180:0002:ffff:ffff:ffff:ffff |
2401:4900:2180:0003::/64
Network range |
2401:4900:2180:0003:0000:0000:0000:0000 - |
|
2401:4900:2180:0003:ffff:ffff:ffff:ffff |
2401:4900:2180:0004::/64
Network range |
2401:4900:2180:0004:0000:0000:0000:0000 - |
|
2401:4900:2180:0004:ffff:ffff:ffff:ffff |
This what you're after?