| 21ST CENTURY EDUCATION SERVICES LLC | — | 19941142767 | 1994-12-22 | Dissolved | |
| 21ST CENTURY EDUCATION SOLUTIONS, INC. | — | 20131429987 | 2013-07-24 | Inactive | PARKER |
| 21ST CENTURY EDUCATIONAL FOUNDATION, INCORPORATED | — | 19951072174 | 1995-06-02 | Dissolved | AVON |
| 21ST CENTURY ELECTRIC, INC. | — | 19941068657 | 1994-06-16 | Dissolved | LITTLETON |
| 21ST CENTURY ENTERTAINMENT AND RETAIL COMPLEX, LLC | — | 20041102443 | 2004-03-18 | Dissolved | DENVER |
| 21ST CENTURY EXECUTIVE TALENT, LLC | — | 20031389365 | 2003-12-09 | Dissolved | SNOWMASS VILLAGE |
| 21ST CENTURY FINANCE, LLC | — | 20001254502 | 2000-12-28 | Revoked | WAUSAU |
| 21ST CENTURY FINANCIAL SERVICES L.L.C. | — | 19981151659 | 1998-08-20 | Dissolved | GREELEY |
| 21ST CENTURY FITNESS, INC. | — | 19991002873 | 1999-01-07 | Dissolved | |
| 21ST CENTURY FUNDING INC. | — | 20041220949 | 2004-06-24 | Inactive | COLORADO SPRINGS |
| 21ST CENTURY HEALTH TECHNOLOGIES, INC. | — | 19971015525 | 1997-01-31 | Dissolved | GRAND JUNCTION |
| 21ST CENTURY HOLDINGS CORP | — | 20091614759 | 2009-11-23 | Inactive | DENVER |
| 21ST CENTURY INFORMATION TECHNOLOGIES, LLC | — | 19971128658 | 1997-08-13 | Dissolved | GREENWOOD VILLAGE |
| 21ST CENTURY INSURANCE COMPANY | — | 20001149170 | 2000-08-01 | Active | Woodland Hills |
| 21ST CENTURY INVESTMENT CLUB, L.L.C. | — | 19991061273 | 1999-04-01 | Inactive | COLORADO SPRINGS |
| 21ST CENTURY INVESTMENT GROUP, LLC | — | 20001040517 | 2000-02-25 | Dissolved | DENVER |
| 21ST CENTURY INVESTMENTS LLC | — | 19951069882 | 1995-05-30 | Active | Greeley |
| 21ST CENTURY JEEVES, INC. | — | 19981066639 | 1998-04-09 | Inactive | DENVER |
| 21ST CENTURY KIDS LLC | — | 20201445930 | 2020-05-23 | Inactive | CHICAGO |
| 21ST CENTURY LODGING, LTD. | — | 19871555496 | 1984-01-31 | Active | |
| 21ST CENTURY MAILING, LLC | — | 19991217864 | 1999-11-19 | Dissolved | DENVER |
| 21ST CENTURY MARKETING AND RESEARCH OF COLORADO LLC | — | 20041024545 | 2004-01-21 | Dissolved | DENVER |
| 21ST CENTURY MEDIA, INC. | — | 20161187730 | 2016-03-17 | Dissolved | Denver |
| 21ST CENTURY MOBILE ELECTRONICS, INC. | — | 19981231907 | 1998-12-30 | Inactive | NORTHGLENN |
| 21ST CENTURY MORTGAGE SERVICES LLC | — | 20001006505 | 2000-01-11 | Dissolved | GREELEY |
| 21ST CENTURY PAINTING & MAINTENANCE, INC. | — | 20021194292 | 2002-07-17 | Active | Johnstown |
| 21ST CENTURY PRODUCTS, INCORPORATED | — | 19931020505 | 1993-02-25 | Inactive | LONGMONT |
| 21ST CENTURY PROPERTIES, LLC | — | 20021002218 | 2002-01-07 | Inactive | Clifton |
| 21ST CENTURY RESOLUTIONS LLC | — | 20001005343 | 2000-01-10 | Dissolved | AURORA |
| 21ST CENTURY SCIENTIFIC INC | — | 20261595860 | 2026-05-20 | Active | DENVER |
| 21ST CENTURY SERVICES, Inc. | — | 20021227911 | 2002-08-19 | Dissolved | AURORA |
| 21ST CENTURY SOLUTIONS GROUP, INC. | — | 20001001013 | 2000-01-04 | Inactive | COLORADO SPRINGS |
| 21ST CENTURY SPORTS, INC. | — | 19931118205 | 1993-10-21 | Dissolved | |
| 21ST CENTURY TECHNOLOGIES, INC. | — | 19931044331 | 1993-04-27 | Active | Denver |
| 21ST CENTURY TOURS AND TRAVEL, INC. | — | 20011177858 | 2001-09-12 | Dissolved | Aurora |
| 21ST CENTURY TOYS, INC. | — | 20071467728 | 2007-10-10 | Inactive | San Leandro |
| 21ST CENTURY TRAVEL, LLC | — | 19981216496 | 1998-12-08 | Dissolved | DENVER |
| 21ST CENTURY TRUSS & COMPONENTS, INC. | — | 20021037773 | 2002-02-15 | Inactive | AURORA |
| 21ST CENTURY VENTURES CORP. | — | 19961108790 | 1996-08-19 | Dissolved | GARLAND |
| 21ST DELI LLC | — | 20031300595 | 2003-09-18 | Dissolved | LONGMONT |
| 21ST DEVELOPMENT COMPANY, INC. | — | 19991240710 | 1999-12-22 | Dissolved | |
| 21ST MORTGAGE CORPORATION | — | 19961086896 | 1996-07-01 | Active | KNOXVILLE |
| 21ST PACIFIC CORPORATION | — | 20021232489 | 2002-08-22 | Inactive | Fort Collins |
| 21ST STREET CAR WASH, INC. | — | 19871516329 | 1983-04-12 | Dissolved | COLORADO SPRINGS |
| 21ST STREET MANOR TOWNHOME ASSOCIATION | — | 20021038591 | 2002-02-15 | Active | Pueblo |
| 21ST STREET, LLC | — | 19941038957 | 1994-04-01 | Inactive | ENGLEWOOD |
| 21ST. CENTURY PROMOTIONS LLC | — | 20001169417 | 2000-08-30 | Inactive | DENVER |
| 21TRUST, LLC | — | 20131013725 | 2013-01-07 | Inactive | Sterling |
| 21TarasBandLLC | — | 20191052045 | 2019-01-21 | Dissolved | Lakewood |
| 21Ten Holdings LLC | — | 20248216527 | 2024-11-18 | Active | Loveland |