example

public static void main(String[] args) {

        String number = "835989102311"; // i'm lazy to use scanner every time.. 
        int biggest = Integer.parseInt(String.valueOf(number.charAt(0)));
        int smallest = biggest;
        int sum = biggest;
        double average;
        int length = number.length();

        for (int i = 1; i < number.length(); i++) {
           if (charToInteger(number.charAt(i)) > biggest ) {
               biggest = charToInteger(number.charAt(i));
           }
            if (charToInteger(number.charAt(i)) < smallest ) {
                smallest = charToInteger(number.charAt(i));
            }
            sum += charToInteger(number.charAt(i));
        }

        average = ((double) sum / length);
        System.out.println("the number : " + number);
        System.out.println("biggest number : " + biggest);
        System.out.println("smallest number : " + smallest);
        System.out.println("sum of number : " + sum);
        System.out.println("average of number : " + average);

        int finalBiggest = biggest;
        int biggestRepeated = Arrays.stream(number.split("")).toList().stream().filter((e) -> Integer.valueOf(e) == finalBiggest).toList().size();
        int finalSmallest = smallest;
        int smallestRepeated = Arrays.stream(number.split("")).toList().stream().filter((e) -> Integer.valueOf(e) == finalSmallest).toList().size();
        System.out.println("biggest number repeated : " + biggestRepeated);
        System.out.println("smallest number repeated : " + smallestRepeated);
    }

    public static int charToInteger(char s) {
        return Integer.parseInt(String.valueOf(s));
    }