Exhibit 21.1

Significant Subsidiaries of the Registrant

1. Diamondback E&P LLC, a Delaware limited liability company

2. Diamondback O&G LLC, a Delaware limited liability company

3. Energen Corporation, an Alabama corporation

4. Energen Resources Corporation, an Alabama corporation

5. Rattler Midstream LP, a Delaware limited partnership

6. Rattler Midstream Operating LLC, a Delaware limited liability company

7. Viper Energy Partners LP, a Delaware limited partnership

8. Viper Energy Partners LLC, a Delaware limited liability company

9. QEP Resources, Inc., a Delaware corporation

10. QEP Energy Company, a Delaware corporation