21 Ọktoba bu ubochi nke 21st (nke iri abụọ na out) na onwa ana kpo Ọktoba. Na Gregorian calender, 21 Ọktoba bu ubochi nke 294th (295th na afo nke ana-kpo leap year) na afo. Anyi nwere agugu ubochi 71 du mgbe afo na agwu.