Math · 2
What is a 'perfect number'?
Answer
A number whose factors sum to itself
A perfect number is a positive integer that equals the sum of its proper divisors (all divisors except the number itself). For example, 6 equals 1 + 2 + 3, and 28 equals 1 + 2 + 4 + 7 + 14. Perfect numbers are rare—only 51 are known as of 2024, and mathematicians still investigate whether infinitely many exist. Ancient Greeks considered them mystically significant.
💡 Did you know?
Known perfect numbers end only in 6 or 28 (like 6, 28, 496, 8128).
Other options people guess
- A number divisible by 10
- A prime number
- A Fibonacci number
Topics
- number-types
- number-theory
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