Last level is 36. 72277. Game isn't that bad or hard. Some levels took half a dozen tries or so, but they are all beatable without flukes. 36 levels though is more than enough, not interested in playing more or using level editor.
51282... gets boring late in game. Still fun to restart an get axe. The button that links to your site is in a bad spot, be better in the top right corner, that way it won't be clicked by accident while playing.
Covert_Elite's comments