I am the smallest number, having four different prime factors. Can you find me?

Find the prime factors and their product:

As we know, the smallest four prime numbers are $2,3,5,7$.

So, the product of these numbers will be the smallest number having four different prime factors.

Therefore, the required number $=2\times 3\times 5\times 7$

$\Rightarrow$ the required number $=210$

Hence, the smallest number having four different prime factors number is $210$.