var dec = 1456741;
var hex = "163A65";


// Zamieniamy i zapisujemy do tablicy
var tab = [];
while(dec > 0) {
        tab.push(dec % 16);
        dec /= 16;
        dec = dec | 0;
}

// Drukujemy wypisując od tyłu
for(var i = tab.length; i >= 0; i--) {
        var c = tab[i];
        if (c < 10){
                console.log(c);
        } else if (c == 10){
                console.log("A");
        } else if (c == 11){
                console.log("B");
        } else if (c == 12){
                console.log("C");
        } else if (c == 13){
                console.log("D");
        } else if (c == 14){
                console.log("E");
        } else if (c == 15){
                console.log("F");
        }
}


var base = 1;
var r = 0;
for(var i = hex.length - 1; i >= 0; i--) {
        var c = hex[i];
        var d;
        switch(c){
                case '0': d = 0;  break;
                case '1': d = 1;  break;
                case '2': d = 2;  break;
                case '3': d = 3;  break;
                case '4': d = 4;  break;
                case '5': d = 5;  break;
                case '6': d = 6;  break;
                case '7': d = 7;  break;
                case '8': d = 8;  break;
                case '9': d = 9;  break;
                case 'A': d = 10; break;
                case 'B': d = 11; break;
                case 'C': d = 12; break;
                case 'D': d = 13; break;
                case 'E': d = 14; break;
                case 'F': d = 15; break;
        }
        r += d * base;
        base *= 16;
}
console.log(r);