vampire number

Fetched 2026-10-26 (cache).

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Noun

1. {{lb|en|math}} A [[composite number|composite]] [[natural number]] with an [[even]] number of [[digit]]s that can be [[factor]]ed into two natural numbers (called "[[fang]]s") each with half as many digits as the original number, and where the two factors contain precisely all the digits of the original number, in any order, counting multiplicity.

Source: Wiktionary · CC BY-SA 4.0 (Wiktionary dump) · cached copy, not a rewrite.