To calculate the price of Bitcoin (BTC) if its market cap reaches $20 trillion, you can use this formula:

Price per BTC = Market Cap / Circulating Supply

As of now, the circulating supply of BTC is approximately 19.7 million coins.

So:

Price = $20,000,000,000,000 / 19,700,000

Price ≈ $1,015,228.43 per BTC