You cannot use numbers as object keys. This is syntax error. Modify your object keys like that {"key_207": "402", ...}
Also to print result you should use <%= key_207 %>
instead of <% =key_207 %>
The best way to fix this issue is to modify server response on the server side.
But also you can try do this (I'm not sure if it will work in all browsers):
var res = {207: "402", 208: "400"};
console.log(res[207]); // -> 402
So you need to pass your model to template inside some object and acces to key in the way above:
__template__({data:this.model.toJSON()})
And then:
<%= data[207] %>