  The role of bremsstrahlung in the emission from hot accretion flows around
slowly accreting supermassive black holes is not thoroughly understood. In
order to appraise the importance of bremsstrahlung relative to other radiative
processes, we compute spectral energy distributions (SEDs) of accretion disks
around slowly accreting supermassive black holes including synchrotron
radiation, inverse Compton scattering, and bremsstrahlung. We compute SEDs for
(i) four axisymmetric radiative general relativistic magnetohydrodynamics
(RadGRMHD) simulations of $10^{8}M_{\odot}$ black holes with accretion rates
between $10^{-8}\dot{M}_{\text{Edd}}$ and $10^{-5}\dot{M}_{\text{Edd}}$, (ii)
four axisymmetric RadGRMHD simulations of M87$^\ast$ with varying dimensionless
spin $a_\ast$ and black hole mass, and (iii) a 3D GRMHD simulation scaled for
Sgr A$^\ast$. At $10^{-8}\dot{M}_{\text{Edd}}$, most of the luminosity is
synchrotron radiation, while at $10^{-5}\dot{M}_{\text{Edd}}$ the three
radiative processes have similar luminosities. In most models, bremsstrahlung
dominates the SED near $512\text{ keV}$. In the M87$^\ast$ models,
bremsstrahlung dominates this part of the SED if $a_{\ast} = 0.5$, but inverse
Compton scattering dominates if $a_{\ast}= 0.9375$. Since scattering is more
variable than bremsstrahlung, this result suggests that $512\text{ keV}$
variability could be a diagnostic of black hole spin. In the appendix, we
compare some bremsstrahlung formulae found in the literature.
