App can't be deleted having no name, just numbers
First, try resetting your home screen layout

Resetting your iPhone's home screen layout should clear icons from apps that aren't downloaded (the relevant app icon appears to not be downloaded). This only involves moving icons around to suit your desire after the reset, no other data will be lost.

Go to Settings > General > Reset > Reset Home Screen Layout.

Tip: take pictures of your old layout before resetting to make the process smoother.



If that doesn't work, do a factory reset

Doing a factory reset and restoring your phone from a backup should fix this issue because the reset will clear all of your app icons and start the home screen from scratch.

Here's how to do that:


Back up your iPhone to either iTunes or iCloud (if you choose iTunes, make sure to do a complete backup). How do I backup my iPhone?
Perform a factory reset of the iPhone after the backup completes in Settings > General > Reset. How do I factory reset my iPhone?
During setup, choose to restore your iPhone from another iPhone and choose the backup you just made. How do I restore my iPhone's data from a backup?
Watch as all your data returns (allow a few hours for apps and photos to re-download), almost definitely without the odd app icon in question.


Note: data from apps that specifically request data not be backed up (like Google Authenticator) will be lost.



tl;dr: try resetting home screen layout first, but if that fails you'll need to do a factory reset.



Fun tidbit: You just found out Spotify's SKU, a unique ID for an app in the Apple system that is not seen by users.