`btshowmetainfo`, formerly included in the BitTorrent distribution but now largely installed with BitTornado (a fork of the BitTorrent 3.x codebase), does just that.
$ btshowmetainfo amd64cd-5.1.2.iso.torrent
btshowmetainfo 20030621 - decode BitTorrent metainfo files
metainfo file.: amd64cd-5.1.2.iso.torrent
info hash.....: e30c05f2330ba4869eefb90bf5978a505303b235
file name.....: amd64cd-5.1.2.iso
file size.....: 253325312 (966 * 262144 + 94208)
announce url..: