YouTube Data API v3 is not getting the correct subscribers count

I am using the YouTube Data API v3 for my work, but it does not get the right subscribers count when I ask for that.

In my code I use this URL:

https://www.googleapis.com/youtube/v3/channels?part=statistics&forUsername=" + MY_USERNAME +"&key=" + MY_KEY

and I get this JSON back:

{"kind": "youtube#channelListResponse","etag": "jEJnVwl_Vgc3tM1asn0kb2Mu7as","pageInfo": {"totalResults": 1,"resultsPerPage": 5  },"items": [    {"kind": "youtube#channel","etag": "CcPFuF-ke8OIYEvfXXCaktL89BA","id": "UC-lHJZR3Gqxm24_Vd_AJ5Yw","statistics": {"viewCount": "26294085594","commentCount": "0","subscriberCount": "107000000","hiddenSubscriberCount": false,"videoCount": "4223"      }    }  ]}

What is good for me is subscriberCount in the items. This JSON result is a test I did for PewDiePie's channel, but I expect the number change every time I refresh due to his fame; and if you look carefully you know it is not even the right number.

Is there a way to get the full number?