Number with maximum number of prime factors | Java program to find integer having maximum number of prime factor in first N natural numbers ; Return smallest number having maximum prime factors . ; default value of boolean is false ; Sieve of eratosthenes ; Storing prime numbers . ; Generating number having maximum prime factors . ; Driver program
import java . util . Vector ; public class GFG { static int maxPrimefactorNum ( int N ) { boolean arr [ ] = new boolean [ N + 5 ] ; for ( int i = 3 ; i * i <= N ; i += 2 ) { if ( ! arr [ i ] ) { for ( int j = i * i ; j <= N ; j += i ) { arr [ j ] = true ; } } } Vector < Integer > prime = new Vector < > ( ) ; prime . add ( prime . size ( ) , 2 ) ; for ( int i = 3 ; i <= N ; i += 2 ) { if ( ! arr [ i ] ) { prime . add ( prime . size ( ) , i ) ; } } int i = 0 , ans = 1 ; while ( ans * prime . get ( i ) <= N && i < prime . size ( ) ) { ans *= prime . get ( i ) ; i ++ ; } return ans ; } public static void main ( String [ ] args ) { int N = 40 ; System . out . println ( maxPrimefactorNum ( N ) ) ; } }