No. The first two "perfect numbers" are 6 and 28.
5 and 2 are perfect numbers
The only two are 9 and 16.
81. They are the perfect squares of numbers starting from 5.81. They are the perfect squares of numbers starting from 5.81. They are the perfect squares of numbers starting from 5.81. They are the perfect squares of numbers starting from 5.
That could either be "What numbers have 5 factors" or "What numbers have 2 and 5 as factors." Prime numbers to the fourth power, like 16 and 81, have 5 factors. Any multiple of 10 has 2 and 5 as a factor.
5 and 10 or 5 and any multiple of 5 for a start
Perfect squares are positive. A smallest negative number doesn't exist. The four smallest prime numbers are 2, 3, 5 and 7. The smallest perfect square would have to be 2^2 x 3^2 x 5^2 x 7^2 or 44,100
Since the number 10 has the prime factorization of 2 x 5, any multiple of 10 has the numbers 2 and 5 in their prime factorization.
Any of their multiples
Any of its factors such as 2, 5 and 37
Any number divisible by 10
Perfect numbers are numbers where all the factors add to that number. For example 6's factors are 1,2, and 3 and 1+2+3=6. Therefore the next perfect number isn't until 28 which is 1,2, 4, 7, 14 where 1+2+4+7+14= 28 An almost perfect number is a number which, when adding all of its proper divisors (all divisors except himself), gives you one less, or one more then the number itlself. Up to now all known almost perfect numbers are 2^n. So to answer your question, the 2 almost perfect numbers between 5 and 20 are 8 and 16. Divisors of 8: 1,2,4 -----> 1+2+4=7 Divisors of 16: 1,2,4,8 -----> 1+2+4+8=15
Yes. The only known almost perfect numbers are the powers of 2. 32 = 2^5 is an almost perfect number. It has not yet been proved whether {x: x = 2^n for n in N} = {x: x is an almost perfect number}.