For those unfamiliar with it: options are usually quoted per-share (even though almost all of them are sold in contracts of 100 shares), because it makes calculating the break even price a lot easier. For a put costing $20 on a $165 strike, the break even at expiration is $145.

Also, you never buy long dated puts ATM in bull markets with the intention of hedging. It's usually much further OTM, since it becomes a lot cheaper. Right now all options are very expensive due to high implied volatility.