As a 180 pound male I find the RDA for the essential amino acids total 17.5 grams. However, the RDA for protein is 64.8 grams. Where does this nearly 4x difference come from?
In the human body, there are 21 amino acids (AA) that can form proteins (Britannica). Only 9 of them are essential, meaning you have to obtain them from food; the other 12 can be synthesized in your body (MedlinePlus).
Most food proteins contain most essential and nonessential AA, so to get 17.5 g of essential AA from proteins, you need to consume more than 17.5 g of them. Anyway, 65 g of protein (RDA) will probably provide more than 17.5 g of essential AA, because RDA does not include only the essential amount of protein but a bigger amount with a wide safe margin.