WhatsApp is notorious for chain messages claiming secret codes unlock hidden features (e.g., *#*#4636#*#* for Android). "211431" may have circulated as a fake "debug code" to make WhatsApp faster. Spoiler alert:
It fits the format of a 6-digit WhatsApp registration code, which users are frequently warned never to share with others for security reasons. whatsapp 211431 better
If is a specific internal ID from a university library (like a Student ID or Course Code) or a specific DOI suffix, here is how to locate the exact text: WhatsApp is notorious for chain messages claiming secret