from math import floor
def f(n, e):
    if e <= 3:
        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:
        for x in range(1, 10 ** 18):
            if x ** e > n:
                return -1
            if x ** e == n:
                return x

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

if e == 1:
    print(-1)
    exit()
# print(b)
ans = 10 ** 20
for j in divisors(e):
    if j == e:
        continue
    x = b ** j
    if len(divisors(x)) == e // j:
        ans = min(ans, x)

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