I think it is a 1821 with the wear and surface damage on the coin giving you the impression of a 4 in an area close to where the 2 should be. The 2 would be spaced closer to the 8 then the 4 is. It would be quite a find if it were 1841 and I shared your interest in giving it a long and hard look. Good luck I hope you are right.
I thought it to be a counterfeit as I placed quotes around the title. Below find images of what appears to be a genuine 1826 S 1/2 Stuiver being sold on Ebay. Seems to me the fonts on the coin in hand are inconsistent and crude compared with the '26. Of course you correctly point out that the damage makes it difficult to say it is a 4 with confidence...it just appears so.
I found hundreds, maybe thousands, of these types in the town and village markets of Indonesia -- especially in that part of Borneo that is Indonesia. As I would often have many of the same dates to compare, I found that some dates were made with markedly differing dies. The crown and the shield, such as in this case, may have been relatively uniform, but the remainder of the pattern could vary and often be quite crude, and often parts of the coin weakly struck, as is your coin. I suspect there were counterfeits of these copper coins, but these should be contemporary counterfeits. At least I considered such on some of my coins. I make no such judgement on your coin. From the photographs, I'd say it was likely authentic.
