After some googling, the answer is VY Canis Majoris, which has a radius that's around 2000 times the one of the sun, which in turn has a radius that's around 109 times the one of the earth.
How large is that? Watch the following video and you'll see at the end how large the sun is compared to VY Canis Majoris:
Now, can you imagine how small human being is? In that sense, how big is the problem that's puzzling you today? Not that big really :)
P.S. Just to give you another perspective how ridiculously tiny the earth is in this gigantic universe, look at the following two images :P
Image from Wikimedia.org