/usr/lib/linux-tools/4.4.0-51-lowlatency/cpupower is in linux-tools-4.4.0-51-lowlatency 4.4.0-51.72.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/4.4.0-51-lowlatency/../../linux-tools-4.4.0-51/cpupower