/usr/lib/x86_64-linux-gnu/libdjvulibre.so.21 is in libdjvulibre21 3.5.25.4-4+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libdjvulibre.so.21.4.0
/usr/lib/x86_64-linux-gnu/libdjvulibre.so.21.4.0