Shuffle a integer using recursive function

convert it to a string?

A = 130

def shuffle(A):
    A = str(A)
    if len(A) <= 2:
        return int(A)
    return int((A[0] + A[-1]) + str(shuffle(A[1:-1])))

Without converting to a string:

def shuffle(x):
    if x < 100:
        return x
    t = x
    l = 0
    while t > 0:
        t //= 10
        l += 1
    a = x // 10 ** (l-1) * 10 ** (l-1)
    b = (x % 10) * 10 ** (l-2)
    return a + b + shuffle((x - a) // 10)

and the tests work:

>>> shuffle(123456)
162534
>>> shuffle(310)
301