Also, according to the man page:
apt-cache showpkg <package_name>
can also be used to:
...display information about the packages listed on the command line. Remaining arguments are package names. The available versions and reverse dependencies of each package listed are listed, as well as forward dependencies for each version. Forward (normal) dependencies are those packages upon which the package in question depends; reverse dependencies are those packages that depend upon the package in question. Thus, forward dependencies must be satisfied for a package, but reverse dependencies need not be.
Ex:
apt-cache policy conky
conky:
Installed: (none)
Candidate: 1.10.3-1
Version table:
1.10.3-1 500
500 http://us.archive.ubuntu.com/ubuntu yakkety/universe amd64 Packages
500 http://us.archive.ubuntu.com/ubuntu yakkety/universe i386 Packages