def product_list(request, slug=None, category_slug=None, show=8):
    categories = Category.objects.prefetch_related('subcategory').all().order_by('name')
    products_list = Product.objects.filter(available=True)
    if category_slug:
        subcategory = get_object_or_404(SubCategory, slug=slug)
        products_list = products_list.filter(subcategory=subcategory)
        page = request.GET.get('page')
        if request.is_ajax():
            show = request.GET.get('show')
        paginator = Paginator(products_list, show)
        try:
            products = paginator.page(page)
        except PageNotAnInteger:
            products = paginator.page(1)
        except EmptyPage:
            products = paginator.page(paginator.num_pages)
        return render(request, 'product.html', {'subcategory': subcategory, 'products': products,
                                                'categories': categories})
    return render(request, 'home.html', {'categories': categories})
 

$('#input-limit').on('change', function(){
        $.get(document.location.href+'?show='+$('#input-limit option:selected').text());
    });

http://127.0.0.1:8000/phones-tablets/phones/?show=25

 paginator.num_pages