  We present the next-to-leading-order event-by-event EKRT model predictions
for the centrality dependence of the charged hadron multiplicity in the
pseudorapidity interval $|\eta|\le 0.5$, and for the centrality dependence of
the charged hadron flow harmonics $v_n\{2\}$ obtained from 2-particle
cumulants, in $\sqrt{s_{NN}}=5.44$ TeV Xe+Xe collisions at the CERN Large
Hadron Collider. Our prediction for the 0-5 \% central charged multiplicity is
$dN_{\rm ch}/d\eta =1218\pm 46$. We also predict $v_n\{2\}$ in Xe+Xe collisions
to increase more slowly from central towards peripheral collisions than those
in a Pb+Pb system. We find that at $10 \dots 50$\% centralities $v_2\{2\}$ is
smaller and $v_3\{2\}$ is larger than in the Pb+Pb system while $v_4\{2\}$ is
of the same magnitude in both systems. We also find that the ratio of flow
harmonics in Xe+Xe collisions and in Pb+Pb collisions shows a slight
sensitivity to the temperature dependence of the shear-viscosity-to-entropy
ratio. As we discuss here, the new nuclear mass-number systematics especially
in the flow harmonics serves as a welcome further constraint for describing the
space-time evolution of a heavy-ion system and for determining the shear
viscosity and other transport properties of strongly interacting matter.
