Only about 5 MB compressed. Interesting to note is that even though the extension and MIME type claim it's a png, Firefox claims it's actually a jpeg. Throwing it at a couple different pieces of software, they all appear to open it with either file extension (so presumably they're going off the file header rather than the actual extension).
File starts with 0xffd8ff, so it's a jpeg. Guess someone uploaded the wrong file.