I am aware of the fact that Prototypes are object literal. So methods and properties can be defined on them. Function.prototype has some method like apply, call, bind, toString etc. So I thought a function's prototype should be a object literal. But I ran following code and encountered that Function.prototype is of type function !
console.log(typeof(Function.prototype)); // function
How come it is not a object literal itself ?
From the specification:
The Function prototype object is the intrinsic object %FunctionPrototype%. The Function prototype object is itself a built-in function object. When invoked, it accepts any arguments and returns undefined. It does not have a [[Construct]] internal method so it is not a constructor.
NOTE
The Function prototype object is specified to be a function object to ensure compatibility with ECMAScript code that was created prior to the ECMAScript 2015 specification.
(my emphasis)
If we go to the ES5 spec, it says:
The Function prototype object is itself a Function object (its [[Class]] is "Function") that, when invoked, accepts any arguments and returns undefined.
...without offering any explanation for why that would be the case. That language is essentially unchanged in ES1, ES2, ES3, and ES5. I think the original idea was basically that that was what gave it its function-ness, although typeof (even in ES1) didn't look at the internal [[Class]], it looked at whether the thing implemented [[Call]] (as it still does). When something goes back all the way to ES1, one frequently has to just invoke the "because Eich did the first JavaScript in 10 days and yeah, weird stuff happens when you do that" argument. :-)
Side note: By "object literal" I take it you mean "plain object." (An "object literal" — what the specifiation calls an object initializer — is just a way to write an object in source code. There are other ways to create plain objects.)