[NeoN]

var data = 4123;
alert(~~(data/3600)+":"+~~((data%3600)/60)+":"+data%3600%60);

или

var data = 4123;
var h = ~~(data/3600);
var m = ~~((data%3600)/60);
var s = data%3600%60;
alert(h+":"+m+":"+s);