ES6 - Attempting to console.log(arguments.length)

Question

let args = () => {   
    console.log(arguments.length);
}; 
    args(2,4,5,6,72);

The above returns an error which says, "arguments is not defined."

However, ES5 syntax works are expected (see below):

var args = function() {
   console.log(arguments.length);
};
   args(2,4,5,6,72);

I would really appreciate an explanation and a remedy to this problem I have run into when using the ES6 syntax. Thanks.