In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum). Equivalently, a perfect number is a number that is half the sum of all of its positive divisors (including itself) i.e. σ1(n) = 2n.
Read more about Perfect Number: Examples, Discovery, Even Perfect Numbers, Odd Perfect Numbers, Minor Results, Related Concepts
Famous quotes containing the words perfect and/or number:
“Your good mother tells me you are feeling very badly in your new situation. Allow me to assure you it is a perfect certainty that you will, very soon, feel better—quite happy—if you only stick to the resolution you have taken to procure a military education. I am older than you, have felt badly myself, and know, what I tell you is true. Adhere to your purpose and you will soon feel as well as you ever did.”
—Abraham Lincoln (1809–1865)
“Again, the great number of cultivated men keep each other up to a high standard. The habit of meeting well-read and knowing men teaches the art of omission and selection.”
—Ralph Waldo Emerson (1803–1882)