Vampire Number Checker
Find all unordered equal-digit factor fangs whose combined decimal multiset matches candidate; both trailing-zero fangs excluded, 1–6 digit bounded search and odd lengths false.
Description
A vampire number has two equal-length factor fangs whose combined digits match its own decimal digits.
A vampire number has two equal-length factor fangs whose combined digits match its own decimal digits. Both fangs ending in zero are excluded from the definition used here.1
Find all unordered equal-digit factor fangs whose combined decimal multiset matches candidate; both trailing-zero fangs excluded, 1–6 digit bounded search and odd lengths false.
When to use Vampire Number Checker
Use this tool to find all unordered equal-digit factor fangs whose combined decimal multiset matches candidate; both trailing-zero fangs excluded, 1–6 digit bounded search and odd lengths false.
Choose the integer, sequence, coefficients or function parameters for your calculation. Follow the stated ordering, domain and size limits.
How to use Vampire Number Checker and understand its results
- Choose the integer, sequence, coefficients or function parameters for your calculation. Follow the stated ordering, domain and size limits.
- Enter candidateInteger using the field table and calculation rules, then run the tool.
- Read vampireFangPairs, isVampireNumber. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| candidateInteger | Candidate integer | number | Required |
Enter an integer from 1 to 999,999. Odd digit lengths return false and no pairs. Otherwise search unordered equal-digit factors up to sqrt(n), exclude two trailing-zero fangs and return all matching pairs in search order.
fang product = n and sorted fang digits = sorted candidate digits Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| vampireFangPairs | Vampire fang pairs | list of list of number |
| isVampireNumber | Is vampire number | boolean |
{
"input": {
"candidateInteger": 1260
},
"output": {
"vampireFangPairs": [
[
21,
60
]
],
"isVampireNumber": true
}
}Limitations and assumptions
The search covers only the bounded candidate and this fang convention. It is not a digit-palindrome test.
Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use Balanced Number Checker: Compare sums of decimal digit halves, ignoring an odd central digit; arbitrary-length canonical decimal text preserves exact identity, unlike palindrome checks. For a complementary task, use Weird Number Checker: Check exact weirdness as abundance with no subset of distinct proper divisors summing to n; bounded 0/1 knapsack, not abundance alone or an exhaustive integer classification beyond caller n.
References
-
Vampire Number Checker — tool.io
Similar or alternative tools
- Balanced Number Checker
Compare sums of decimal digit halves, ignoring an odd central digit; arbitrary-length canonical decimal text preserves exact identity, unlike palindrome checks.
- Weird Number Checker
Check exact weirdness as abundance with no subset of distinct proper divisors summing to n; bounded 0/1 knapsack, not abundance alone or an exhaustive integer classification beyond caller n.