Project Euler #12 in Julia slower than Python?

My code in Julia, almost identical as the Python code (see below), runs in 4.6 s while the Python version runs in 2.4 s. Obviously there is a lot or room for improvement.

function Problem12()
    #=
     The sequence of triangle numbers is generated by adding the natural
    numbers. So the 7th triangle number would be:
    1 + 2 + 3 + 4 + 5 + 6 + 7 = 28.

    The first ten terms would be:
    1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

    Let us list the factors of the first seven triangle numbers:

     1: 1
     3: 1,3
     6: 1,2,3,6
    10: 1,2,5,10
    15: 1,3,5,15
    21: 1,3,7,21
    28: 1,2,4,7,14,28

    We can see that 28 is the first triangle number to have over five divisors.

    What is the value of the first triangle number to have over five hundred
    divisors?
    =#

    function num_divisors(n)
        res = floor(sqrt(n))
        divs = ()
        for i in 1:res
            if n%i == 0
                append!(divs,i)
            end
        end
        if res^2 == n
            pop!(divs)
        end
        return 2*length(divs)
    end

    triangle = 0
    for i in Iterators.countfrom(1)
        triangle += i
        if num_divisors(triangle) > 500
            return string(triangle)
        end
    end
end

Python version below:

import itertools
from math import sqrt, floor


# Returns the number of integers in the range (1, n) that divide n.
def num_divisors(n):
    end = floor(sqrt(n))
    divs = ()
    for i in range(1, end + 1):
        if n % i == 0:
            divs.append(i)
    if end**2 == n:
        divs.pop()
    return 2*len(divs)


def compute():
    triangle = 0
    for i in itertools.count(1):
        # This is the ith triangle number, i.e. num = 1 + 2 + ... + i =
        # = i*(i+1)/2
        triangle += i
        if num_divisors(triangle) > 500:
            return str(triangle)