Some objects are modeled very large. The modeler leaves it up to the user to scale them to suit. I imagine because different softwares have different conversions when importing an obj file. I'm no expert in modeling. But I know that you can usually select the measurement format in the various modeling programs (English or European, and sometimes Generic). English would be feet, inches, yards. European would be meters and such. Generic is just 1, 2, 3, etc. And then you'd have to figure out how that translates into one of the other formats. Someone may know more about import and export options.
Select only the object and go to the parameters tab and use the scaling slider, not the indifidual ones, the one that affects the entire object. I can't remember what they are. I think X, Y, Z and All. Use All. You can just use the slider, or you can type in a value, which would be a percentage. If it that huge, start with 50% or 40%, until you can see the whole thing in the viewport. Then, bring in a human figure for comparison to fine tune how much it has to be scaled down to look right.
Dana