The vampire numbers were introduced by Clifford A. Pickover in 1994.
Definitions:
A vampire number is a number which can be written as a product of two numbers (called fangs), containing the same digits the same number of times as the vampire number. Example:
1827000 = 210 · 8700
A true vampire number is a vampire number which can be written with two fangs having the same number of digits and not both ending in 0.
Example:
1827 = 21 · 87
All vampire numbers (or just vampires) on the rest of this page are implicitly true. They must clearly have an even number of digits.
A prime vampire number (introduced by Carlos Rivera in 2002) is a true vampire number where the fangs are the prime factors.
The 7 vampires with 4 digits:
1260=21 · 60, 1395=15 · 93, 1435=35 · 41, 1530=30 · 51, 1827=21 · 87, 2187=27 · 81, 6880=80 · 86
The 5 prime vampires with 6 digits:
117067 = 167 · 701, 124483 = 281 · 443, 146137 = 317 · 461, 371893 = 383 · 971, 536539 = 563 · 953
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