162,000=6×5×5×5×6×6×2×3
The primes 2 and 3 do not appear in groups of three. So, 162,000 is not a perfect cube.
In the factorization of 162,000 the prime 2 appears only one time and the prime 3 appears once.
So, if we divide 162,000 by 2×2×3×3=36, then the prime factorisation of the quotient will not contain 2 and 3.
Hence, the smallest natural number by which 162,000 should be divided to make it a perfect cube is 36.