Four Digit Number, C#

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//Write a Boolean expression that checks for given integer if it can be divided (without remainder) by 7 and 5 in the same time. Examples:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int number = 9876;
            
            // gets every digit and creates an array with int elements
            int[] num = new int[4];
            num = ReverseOrder(number);
            
            //creates an array with all digits in a string format
            string[] stringNum = new string[4];
            stringNum = StringArray(num);
            
            //Now that we have converted the digits to string, you can easily use the + operator to create the new numbers and convert them to integer
            
            //calculates the sum of all digits
            int sumOfDigits = (num[0] + num[1] + num[2] + num[3]);
            Console.WriteLine("The sum of digits is: {0}", sumOfDigits);
             
            //Creates the reverse number
            string reverseNumber = stringNum[0] + stringNum[1] + stringNum[2] + stringNum[3];
            Console.WriteLine("The reverse number is: {0}", reverseNumber);
            
            //Exchange 1st and last number
            
            string exchange1st = (stringNum[0] + stringNum[3] + stringNum[2] + stringNum[1]);
            Console.WriteLine("Number after exchanging first and last digit: {0}", exchange1st);
            
            // Exchange 2nd and third number
            
            string exchange2nd = (stringNum[3] + stringNum[1] + stringNum[2] + stringNum[0]);
            Console.WriteLine("Number after exchanging second and third digit: {0}", exchange2nd);
        }
        
        public static int[] ReverseOrder(int number)
        {
            int[] num = new int[4];
            
            num[0] = (number %10);
            number = (number/10);
            
                
            num[1] = (number %10);
            number = (number / 10);
            
            
            num[2] = (number %10);
            number = (number / 10);
            
            num[3] = (number %10);
            
            //Shows all digits
            /*foreach (int numbers in num)
                
            {
                Console.WriteLine(numbers); 
            }*/
            
            return num;
            
        }
        
        public static string[] StringArray(int[] num)
        {
            string[] stringNum = new string[4];
            
            for (int i = 0; i < num.Length; i++)
                
            {
                stringNum[i] = num[i].ToString();
                
            }
            
            return stringNum;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0.07 sec, absolute running time: 0.09 sec, cpu time: 0.06 sec, average memory usage: 16 Mb, average nr of threads: 4