public static int divisibleBucketNum(int backendNum) {
        while (backendNum > 7) {
            if (backendNum % 2 == 0) {
                backendNum = backendNum / 2;
            } else if (backendNum % 3 == 0) {
                backendNum = backendNum / 3;
            } else if (backendNum % 5 == 0) {
                backendNum = backendNum / 5;
            } else if (backendNum % 7 == 0) {
                backendNum = backendNum / 7;
            } else {
                backendNum = backendNum / 2;
            }
        }

        return backendNum;
    }
@Test
    public void testDivisibleByTwo() {
        Assertions.assertEquals(1, CatalogUtils.divisibleBucketNum(1));
        Assertions.assertEquals(2, CatalogUtils.divisibleBucketNum(2));
        Assertions.assertEquals(3, CatalogUtils.divisibleBucketNum(3));
        Assertions.assertEquals(4, CatalogUtils.divisibleBucketNum(4));
        Assertions.assertEquals(5, CatalogUtils.divisibleBucketNum(5));
        Assertions.assertEquals(6, CatalogUtils.divisibleBucketNum(6));
        Assertions.assertEquals(7, CatalogUtils.divisibleBucketNum(7));
        Assertions.assertEquals(4, CatalogUtils.divisibleBucketNum(8));
        Assertions.assertEquals(3, CatalogUtils.divisibleBucketNum(9));
        Assertions.assertEquals(5, CatalogUtils.divisibleBucketNum(10));
        Assertions.assertEquals(5, CatalogUtils.divisibleBucketNum(11));
        Assertions.assertEquals(6, CatalogUtils.divisibleBucketNum(12));
        Assertions.assertEquals(6, CatalogUtils.divisibleBucketNum(13));
        Assertions.assertEquals(7, CatalogUtils.divisibleBucketNum(14));
        Assertions.assertEquals(5, CatalogUtils.divisibleBucketNum(15));
        Assertions.assertEquals(4, CatalogUtils.divisibleBucketNum(16));
        Assertions.assertEquals(4, CatalogUtils.divisibleBucketNum(17));
        Assertions.assertEquals(3, CatalogUtils.divisibleBucketNum(18));
        Assertions.assertEquals(3, CatalogUtils.divisibleBucketNum(19));
        Assertions.assertEquals(5, CatalogUtils.divisibleBucketNum(20));
        Assertions.assertEquals(7, CatalogUtils.divisibleBucketNum(21));
    }