n = int(eval(input()))

ans = 0

for i in range(1,n+1):

    tmp = n//i

    ans += (tmp*(tmp+1)//2)*i

print(ans)
import numba



@numba.njit

def main(n):

    ans = 0

    for k in range(1, n+1):

        for f in range(1,n//k+1):

            ans += k*f

    return ans



n = int(eval(input()))

print((main(n)))
n = int(eval(input()))
ans = 0
for i in range(1, n + 1):
    tmp = n // i
    ans += (tmp * (tmp + 1) // 2) * i
print(ans)

import numba


@numba.njit
def main(n):
    ans = 0
    for k in range(1, n + 1):
        for f in range(1, n // k + 1):
            ans += k * f
    return ans


n = int(eval(input()))
print((main(n)))

+import numba + + +@numba.njit +def main(n): +    ans = 0 +    for k in range(1, n + 1): +        for f in range(1, n // k + 1): +            ans += k * f +    return ans + + -ans = 0 -for i in range(1, n + 1): -    tmp = n // i -    ans += (tmp * (tmp + 1) // 2) * i -print(ans) +print((main(n)))