Flux Density of the Umov Electromagnetic Energy during Uniform Motion of an Extended Electron

— The flux density vector of the electromagnetic energy in the Poynting form and the problem of the electron electromagnetic momentum, associated with this definition, are considered. The alternative flux density definition, i.e., the Umov vector whose value is identical to the Poynting vector only for empty space, is also analyzed. For qualitative comparison of differential and integral values of these two vectors in the case of non-empty space, the model of the extended electron whose charge density is inversely proportional to the quartic distance from the symmetry center is studied. It is shown that the Umov vector in this case appears more universal, since the corresponding energy conservation law does not contain a term responsible for the electromagnetic energy conversion to other energy types.