def f(n, e):
    ok = 0
    ng = 10 ** 18
    while ng - ok > 1:
        mid = ok + ng >> 1
        if mid ** e <= n:
            ok = mid
        else:
            ng = mid
    if ok ** e == n:
        return ok
    else:
        return -1

def divisors(n):
    a = []
    i = 1
    while i * i <= n:
        if n % i == 0:
            a.append(i)
            if n // i != i:
                a.append(n//i)
        i += 1
    
    return a

n = int(input())
if n == 1:
    print(1)
    exit()

for i in range(63, 0, -1):
    x = f(n, i)
    if x == -1:
        continue
    b, e = x, i
    break

if e == 1:
    print(-1)
    exit()

ans = 10 ** 20
for j in divisors(e):
    x = b ** j
    if len(divisors(x)) == e // j:
        ans = min(ans, x)

if ans == 10 ** 20:
    print(-1)
else:
    print(ans)