Perfect Number | Java program to check if a given number is perfect or not ; Returns true if n is perfect ; To store sum of divisors ; Find all divisors and add them ; If sum of divisors is equal to n , then n is a perfect number ; Driver program
class GFG { static boolean isPerfect ( int n ) { int sum = 1 ; for ( int i = 2 ; i * i <= n ; i ++ ) { if ( n % i == 0 ) { if ( i * i != n ) sum = sum + i + n / i ; else sum = sum + i ; } } if ( sum == n && n != 1 ) return true ; return false ; } public static void main ( String [ ] args ) { System . out . println ( " Below ▁ are ▁ all ▁ perfect " + " numbers ▁ till ▁ 10000" ) ; for ( int n = 2 ; n < 10000 ; n ++ ) if ( isPerfect ( n ) ) System . out . println ( n + " ▁ is ▁ a ▁ perfect ▁ number " ) ; } }