  The strongly constrained and appropriately normed (SCAN) semilocal density
functional [J. Sun, A. Ruzsinszky, J. P. Perdew \textit{Phys. Rev. Lett.} {\bf
115}, 036402 (2015)] obeys all 17 known exact constraints for
meta-generalized-gradient approximations (meta-GGA) and includes some medium
range correlation effects. Long-range London dispersion interactions are still
missing, but can be accounted for via an appropriate correction scheme. In this
study, we combine SCAN with an efficient London dispersion correction and show
that lattice energies of simple organic crystals can be improved with the
applied correction by 50\%. The London-dispersion corrected SCAN meta-GGA
outperforms all other tested London-dispersion corrected meta-GGAs for
molecular geometries. Our new method delivers mean absolute deviations (MADs)
for main group bond lengths that are consistently below 1\,pm, rotational
constants with MADs of 0.2\%, and noncovalent distances with MADs below 1\%.
For a large database of general main group thermochemistry and kinetics, it
also delivers a weighted mean absolute deviation below 4 kcal/mol, one of the
lowest for long-range corrected meta-GGA functionals. We also discuss some
consequences of numerical sensitivity encountered for meta-GGAs.
