<div id="number" data-myvalue="<?=$number?>"><?=number_format($number)?></div>

var myvalue = $("#number").data("myvalue");

var myNumber = "2,100,000";

myNumber = parseInt(myNumber.replace(/,/g,''), 10);

console.log(myNumber);

var a = "2,100,000";
a = a.replace(/,/g, ""); //Replace all occurences of "," with ""
a = parseInt(a); //If you know it's an integer
a = parseFloat(a); //If it might be a float
a += 1;
alert(a); //Displays 2100001

var number_string = '2,100,000';
number_string = string.replace(/[^0-9]/gi, ''); // remove non-numeric charachters
var number = parseInt(number_string);  // parse the string to integer