The version you requested (181+deb9u1) is not available, but a newer one is (181+deb9u2). We redirected you there.
This file is indexed.

/usr/bin/vacuumdb is in postgresql-client-common 181+deb9u2.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/bin/../share/postgresql-common/pg_wrapper