>>27625545If you open it in a new tab and look at the URL you'll see that the filename was replaced with a string of numbers. That string is actually what number image was uploaded.
For example, my image filename might be "1439774948370.jpg", but it's the 1,470,665,411,445th image ever posted on 4chan.
It's much more efficient for archival purposes than tumblr's literal arbitrary string of numbers.
