Blocking Kivy application

async.kv

#: kivy 1.11.1

<MainLayout@BoxLayout>:
    palindrome_label: palindrome_label
    prime_label: prime_label
    prime: 100000000
    palindrome: 10000001
    orientation: 'vertical'
    BoxLayout:
        orientation: 'horizontal'
        Label:
            id: palindrome_label
            text: 'The current palindrome is {}'.format(root.palindrome)
        Label:
            id: prime_label
            text: 'The current prime is {}'.format(root.prime)
    Splitter:
        sizable_from: 'top'
        BoxLayout:
            orientation: 'horizontal'
            Button:
                text: 'Get next palindrome'
                on_press: app.update_palindrome()
            Button:
                text: 'Get next prime'
                on_press: app.update_prime()

async_blocking.py

from concurrent.futures import ThreadPoolExecutor
import kivy
from kivy.app import App
from kivy.properties import ObjectProperty, NumericProperty
from kivy.uix.boxlayout import BoxLayout

def is_prime(n):
    '''
    Checks if a number is prime.
    '''
    for i in range(2, n):
        if n % i == 0: return False
    return True

def get_next_prime(n):
    '''
    Returns the next prime number larger than n.
    '''
    n += 1
    while not is_prime(n): n += 1
    return n

def get_next_palindrome(n):
    '''
    Returns the next palindromic number larger than n.
    '''
    n += 1
    while not str(n) == str(n)[::-1]: n += 1
    return n

class MainLayout(BoxLayout):
    palindrome_label = ObjectProperty(None)
    prime_label = ObjectProperty(None)
    palindrome = NumericProperty(1)
    prime = NumericProperty(1)

class AsyncApp(App):
    def build(self):
        self.layout = MainLayout()
        return self.layout
    
    def update_palindrome(self):
        current = self.layout.palindrome
        self.layout.palindrome = get_next_palindrome(current)
    
    def update_prime(self):
        current = self.layout.prime
        self.layout.prime = get_next_prime(current)

if __name__ == '__main__':
    AsyncApp().run()