CC2640R2F: Over-The-Air (OTA) question on CC2640R2F

Part Number:CC2640R2F

Hello, Gurus

I am using CC2640R2F for a wearable application development. 

Somehow I need to include the OTA feature in the firmware design. 

My question is for this purpose, what's the maximum flash size available for my firmwares (IMG A and IMG B)?

The datasheet says "275KB of Nonvolatile Memory Including 128KB of In-System Programmable Flash".

128K is programmable. How about the rest 147K (=275-128)? 

My understanding is that there is only 40K space for user code (including both IMG A and IMG B).

Am I right? If this is the case, it is almost impossible for OTA implementation.

Your comments are appreciated.

thanks.

Kevin