Calculations according to the Hartree–Fock–Bogoliubov method using the non-relativistic Skyrme interaction have proposed Z = 126 as a closed proton shell. In this region of the periodic table, N = 184, N = 196, and N = 228 have been suggested as closed neutron shells. Therefore, the isotopes of most interest are 126, 126, and 126, for these might be considerably longer-lived than other isotopes. Element 126, having a magic number of protons, is predicted to be more stable than other elements in this region, and may have nuclear isomers with very long half-lives. It is also possible that the island of stability is instead centered at 122, which may be spherical and doubly magic. Probably, the island of stability occurs around Z = 114–126 and N = 184, with lifetimes probably around hours to days. Beyond the shell closure at N = 184, spontaneous fission lifetimes should drastically drop below 10 seconds – too short for a nucleus to obtain an electron cloud and participate in any chemistry. That being said, such lifetimes are very model-dependent, and predictions range across many orders of magnitude.