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Cifra Artis Magistra



IUCNN natural numbers species extinction classifications

• Extinct (EX)
• Critically Endangered (CR)
• Endangered (EN)
• Vulnerable (VU)
• Near Threatened (NT)
• Least Concern (LC)

concept 41
by CCPT



Humanity is claiming more and more natural numbers, using them as pawns in the ever-expanding game of generating product serial numbers, phone numbers, calculation results, and more.

Inspired by the IUCN (International Union for Conservation of Nature) – who closely monitor the preservation status of nature’s species – we are launching the IUCNN (International Union for Conservation of Natural Numbers).

We use the Google search engine to determine which numbers have been used. When all numbers of a certain length return search results, that species is considered extinct.

Our research so far has led to the following estimates.

Numbers of length:

• 0, extinct
• 1, extinct
• 2, extinct
• 3, extinct
• 4, extinct
• 5, extinct
• 6, extinct
• 8, extinct
• 9, critically endangered
• 10, endangered
• 11, vulnerable
• 12, near threatened
• 13, least concern

An example of a 10-digit number that is still alive (as of 03.07.2025) is 1311431391. Google returns no search results.
UPDATE: sadly, the number is gone: we got a search result on 16.09.2025 ✝

Help us out by searching for living numbers in lower categories. You will get an honorary mention when we list them here!

IUCNN is available in the portique.