Ruby program to check perfect number

Write a Ruby program to check perfect number

Perfect Number:  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.

class PerfectNumber
  def checkPerfectNumber
    i=1
    sum=0
    puts "Enter the number"
    n = gets.chomp.to_i
    while i < n do 
      sum = (sum + i) if n % i == 0
      i = i + 1
    end
    if sum == n
      puts "Given number is perfect number"
    else
      puts "Given number is not a perfect number"
    end
  end
end

p = PerfectNumber.new 
p.checkPerfectNumber


Output:

Enter the number
 6
Given number is perfect number
=> ni