Distribution of $28$ objects into 4 heaps In how many ways can $28$ different things can be formed into $4$ heaps so that each may contain $7$ things?

Could someone give me slight hint for this particular question.
I'm assuming that the heaps are not labeled.

Object nr.  $28$ can be associated with $6$ other objects in ${27\choose 6}$ ways. The highest ranking left over object can be associated with $6$ other left over objects in ${20\choose6}$ ways, and finally the now highest ranking left over object can be associated with $6$ other left over objects in ${13\choose 6}$ ways. The last heap is what's left over now. The total number of ways therefore comes to
$$N={27\choose 6}\cdot{20\choose6}\cdot{13\choose 6}=19\,688\,264\,481\,600\ .$$
I would say, count of ways = $\binom{28}{7}\cdot\binom{21}{7}\cdot\binom{14}{7}\cdot\binom{7}{7}$