funcion para identificar si un numero es primo o no, si lo es que me retorne el siguiente numero primo sino none

import math
def is_prime(number):
    if number <= 1:
        return False
    else:
        for i in range(2, int(math.sqrt(number))+1):
            if number % i == 0:
                return False
    return True

def find_next_prime(number):
    number += 1
    while not is_prime(number):
        number += 1
    return number

def find_all_prime(number):
    primes = []
    while number > 1:
        number = find_next_prime(number)
        primes.append(number)
        number -= 1
    return primes

find_all_prime(15)