No - it's a standard bolt with a 9/16" head. If it's rounded off, try using a 6-sided impact socket. Failing that, knock on a 14MM socket. It will come out - it's just TIGHT.
If all else fails, grind off the head and replace the bolt. The remaining stud will come out easily once the blade is off.
I use a cheap (£20) chinese-made 12V impact driver just for this job. Never fails.
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