: The "WA" prefix stands for WhatsApp , and the "0013" is a sequential index for images received or sent on that specific day.
If you have received this file as a document or a standard chat image, here is how you can save it permanently to your gallery: On Android
The filename is a structured string that provides information about when the image was created and how it was processed by the app.
: This long prefix is likely a Unix timestamp (in milliseconds) used by a file manager or a cloud backup service (like Google Photos) to ensure a unique filename during a download or sync process.