Error: requireJS config is not a function

My Project structure looks like this -

src
 |- main.js
 |- math.js

math.js is just an AMD module and I am requiring it in main.js

I have installed require.js using npm and requiring it in main.js

//main.js

var rjs = require('requirejs');

rjs.config({
  //Pass the top-level main.js/index.js require
  //function to requirejs so that node modules
  //are loaded relative to the top-level JS file.
  nodeRequire: require,
  
});

rjs(["./math.js"], function(math) {
  console.log(math.add(2, 3));
});

//math.js

define("math", function() {
  function add(a, b) {
    return a + b;
  }
  function subtract(a, b) {
    return a - b;
  }
  function multiply(a, b) {
    return a * b;
  }
  function divide(a, b) {
    return a / b;
  }
  
  return { add, subtract, multiply, divide };
});

While running r.js ./src/main.js, I am getting the below error.

rjs.config is not a function
    at /Users/dheerajmahra/Desktop/learning/different-module-formats/src/main.js:3:5
    at /Users/dheerajmahra/Desktop/learning/different-module-formats/src/main.js:14:2
    at Script.runInThisContext (vm.js:96:20)
    at Object.runInThisContext (vm.js:303:38)
    ....