How does the American Elector system allocate Electors to the states since it’s not based on a set number of people per elector?

How is it decided that electors are allocated to states based on population. I know that the number of electors are decided by population, but how. Of the 435 electors, not including the 3 DC has, the USA (population 336,600,000) should have an average elector per ~773,793, meaning Wyoming (population ~584,000) would have 1 elector while California (population ~38,970,000) would have about 50 electors. So how are the electors allocated? Why are the interior states, who had a relative low population density, were overrepresented by their elector numbers, while the coastal states, which had a comparatively high population density, were underrepresented by their electors? How are the numbers of electors per state determined?