On Prime factorization of 18522, we get,
18522=2×3×3×3×7×7×7
=21×33×73.
We know, a perfect cube should have each prime factor in power of 3.
Here, number of 2's is in power of 1, number of 3's is in power of 3 and number of 7's is in power of 3.
So, we need to remove 2 from the factors to make 18522, a perfect cube.
Hence, the smallest number by which 18522 must be divided to obtain a perfect cube is 2.