21st Century FTC Act This bill eliminates certain requirements with respect to the rulemaking authority of the Federal Trade Commission (FTC). Specifically, the FTC may promulgate a rule under the Administrative Procedure Act defining an unfair or deceptive trade practice without (1) publishing advance notice of the rulemaking, (2) finding a widespread pattern of an applicable unfair practice, or (3) providing the opportunity for an informal hearing. It also limits the opportunity for the FTC or a petitioner of a rule to make additional oral submissions and written presentations while a rule is under judicial review. Further, a court may not set aside a rule promulgated through such notice and comment process on the basis that the FTC failed to complete a regulatory analysis.