/usr/lib/jvm/java-6-openjdk-amd64/bin/rmiregistry is in openjdk-6-jre-headless 6b24-1.11.1-4ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/jvm/java-6-openjdk-amd64/bin/../jre/bin/rmiregistry