What 1947 penny is worth $1.7 million?

I'm curious, could you elaborate on which specific 1947 penny is being referred to that's valued at an astonishing $1.7 million? Is it a particularly rare or unique variant, perhaps with a distinctive mint mark or error? And how did it come to attain such a remarkable price? It's intriguing to think about the factors that might contribute to such a high valuation for a seemingly ordinary coin from decades ago.