A number of interesting systematics and correlations have been deduced by analyzing the criticality data of special actinide nuclides using concepts embodied in the Trombay criticality formula (TCF). The k∞ of fast metal actinide nuclides gives a remarkable linear correlation with the fissility parameter Z2/A. The neutron leakage probability of all fast metal cores characterized using a constant parameter σstd enables computation of the critical mass value of any unknown fissile nuclide knowing only its Z2/A value. Since the neutron leakage probability from dilute fissile solutions is primarily governed by the scattering/slowing down properties of the hydrogen present in water, critical masses and subcritical limits can be predicted for any water-reflected system at any specified hydrogen-to-actinide atomic ratio knowing only the k∞ value of the given fissile solution. In the case of fast fissible actinide systems, the neutron leakage probability can be characterized by a single parameter σstd, but having a slightly different value from that of fast fissile systems. Due to their fission thresholds, however, attempts to deduce any systematics in their k∞ values have not been very successful. The importance of compiling not only critical radius/mass data but also k∞, the critical surface mass density , the degree of reflection parameter Y, etc., has been clarified while preparing criticality data tabulations for ready reference. These quantities can be used along with the TCF to compute core dimensions and fissile inventories required to yield any specified safe subcritical keff value.