12

let tri = function(n){
  return (n/2)*(n+1)
}

let div = function(n){
  let sum = 0;
  for(let I = 1; I*I<n; I++){
    if(n%I == 0){
      sum += 2;
    }
  }
  return sum;
}

let Z = 0;
while(div(tri(Z))<500){
  Z++;
}

console.log( tri(Z) );