The perfect numbers
To who you wouldn't have in your home a perfect number?
Perfect numbers was much impressed the mathematicians of antiquity, very accustomed to play with the numbers. The Greeks and the Jews (old course) used letters to write the figures, whereupon each number could be associated with a Word and allowed esoteric conclusions that would pale to any addict to the pool. For example ' the number 666 associated with "the beast" in Revelation because the written way alludes to the Emperor Nero, which was for the first Christians (and rightly so) little less than a monster. However, 666 is not a perfect number.
On the other hand, the pale 6 is. A "perfect number" is one that coincides with the sum of all its divisors except itself. And 6 complies with the requirement: its divisors are 1, 2, 3, and 1 + 2 + 3 is exactly equal to 6. Both the old and the New Testament commentators did not let be amazed that the number of days that God took to create the world (discarding the seventh day of rest) was just a perfect number. This coincidence was not simply in perplexity, but it came to be used as a theological argument. According to St. Augustine have been able to create God the world instantly, however preferred to employ six days because "the perfection of the number 6 means the perfection of the"
And if you consider that the next perfect number is 28 (sum of 1 + 2 + 4 + 7 + 14), more or less while taking the cycle of the Moon, is to be expected that for a long time the reckoners launched the hunt for perfect numbers. But the perfect numbers are difficult to hunt. And they are few. After the 6 small and vigorous 28, the next perfect number (the third) is 496, the fourth is 8.128 and fifth... 33.550.336!
The sixth already walks the eight billion. The eighth is a 19 digit number. Twenty-four "perfect numbers", are known today really implausible lengths: the twenty fourth perfect number has more than twelve thousand figures. Of course, these numbers are handled and investigated by computer.
And there are mysteries, unsolved mysteries. To begin with, it is not known if there is any odd perfect number. It is not known if there are infinite perfect numbers. No one should be surprised if tomorrow someone announces discovery of the twenty fifth perfect number: not the reader, try it since it is a thankless task. And it is worth this in 1811 by the discoverer of the ninth perfect number (too long to write it here, since it has thirty-seven figures). "Perfect numbers are mere curiosities without any useful."