Untouchable Number | Java program for the above approach ; Function to calculate sum of all proper divisors of num ; Final result of summation of divisors ; Find all divisors of num ; If ' i ' is divisor of ' num ' ; If both divisors are same then add it only once else add both ; Add 1 to the result as 1 is also a divisor ; Function to check if N is a Untouchable Number ; Driver code ; Given Number N ; Function Call
class GFG { static int divSum ( int num ) { int result = 0 ; for ( int i = 2 ; i <= Math . sqrt ( num ) ; i ++ ) { if ( num % i == 0 ) { if ( i == ( num / i ) ) result += i ; else result += ( i + num / i ) ; } } return ( result + 1 ) ; } static boolean isUntouchable ( int n ) { for ( int i = 1 ; i <= 2 * n ; i ++ ) { if ( divSum ( i ) == n ) return false ; } return true ; } public static void main ( String [ ] args ) { int n = 52 ; if ( isUntouchable ( n ) ) System . out . println ( " Yes " ) ; else System . out . println ( " No " ) ; } }