: This is typically a timestamp or a unique ID. If it's a Unix timestamp, 1551547128 translates to approximately March 2, 2019 , at 5:18 PM UTC.
: On Windows, you can typically double-click the file to open it in the Photos app . On macOS, the default program is usually Preview . post_28_IMG_1551547128_1.jpeg
The text post_28_IMG_1551547128_1.jpeg appears to be a specific for a digital image in the JPEG format . Understanding the Filename : This is typically a timestamp or a unique ID