iPadOS 9.2.1 (build 13D15) is an official Apple over-the-air update for the iPad mini 4 (Cellular), released on 2016-01-19T17:59:36Z. The update package is 314.25 MB. This is a delta (partial) update that requires 9.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 51c6b2503510936543270f5a8f903820d2821944.zip.