Double half Heusler alloys are promising materials for utilization in thermoelectric power converters. Recently, the lattice thermal conductivity of 118 such alloys was predicted using machine learning based screening, in particular, five compositions with the lowest thermal conductivity were identified. In this work, within the ab initio approach, we study the electronic and elastic properties of these five double half Heusler alloys considering two possible crystalline modifications - with space groups I-42d and F-43m. It is found that MgZrPd2Bi2, MgHfPd2Bi2, and MgZrPt2Bi2 have a band gap width of less than 0.14 eV, which is smaller than for other compounds of this class and indicates that these compounds can exhibit excellent electronic thermoelectric properties. Moreover, from the analysis of the elastic characteristics, we show that these compounds are ductile and have a low anisotropy of the elastic properties.