Careful Calculation

You are given a single integer N. It's very large, so it's given as a product of several prime powers: N = p1k1 p2k2 ... pmkm. Let's define φ(N) as Euler's totient function -- the number of positive integers less than or equal to N that are relatively prime to N. Let N1 = φ(N). Let N2 = φ(N1). Further, let NX = φ(NX-1) for X > 2. Your task is to find the smallest positive integer X such that NX