  A model for determining the dimensionless spin parameter and mass of the
black hole remnant of black hole-neutron star mergers with arbitrary initial
black hole spin angular momentum, binary mass ratio, and neutron star mass and
cold equation of state is formulated. Tests against numerical-relativity
results are carried out, showing that both the dimensionless spin parameter and
the final mass are accurately reproduced. For the first time, the behaviour of
both quantities and of the l = 2, m = 2, n = 0 quasinormal mode frequency is
inspected throughout the parameter space. Predictions of this frequency may be
exploited to guide gravitational wave modelling and detection efforts, and to
extract physical information from detected gravitational wave signals that
would help us break degeneracies between binary black hole and black
hole-neutron star systems, improve our understanding of compact binary
formation, and constrain the neutron star equation of state.
