Allah is the Creator of everything. This not only includes things in the physical plane, but also things which are abstract and notions which exist in the metaphysical plane, and also other things of which we have no knowledge. He is the Creator of Mathematics as well. One of the names of Allah is Al-Muhsi which translates to The Reckoner, Appraiser, or Accountant. Henry Bayman has said a concise meaning of it would be The Mathematician.
Now mathematics is essentially about abstract systems and deductions that can be drawn within these systems. Mathematical objects have no real existence, they are ideas that exist in the mind. Even that idea may sometimes be only a model of more underlying notion. When a shepherd counts 1,2,3 he may be using the notion of "one sheep", "two sheep", "three sheep" instinctively present in his mind. He is not bothered about any fancy abstract ideas.
So Mathematics is most certainly a part of creation, nothing more then that. However, it must be said that, as the Quran suggests that we should look for signs in the universe to learn more about Allah (Swt). It may be that knowledge of mathematics acquired properly will make us more cognizant of the order, discipline and justice of the laws prevailing physically and metaphysically around us and help us in knowing Allah better. Secondly, for practical reasons Imam Ghazali has said in his book, The Revival of the Religious Sciences, that knowledge of basic mathematics is fard-e-kifaya on the community. If no one has knowledge of basic mathematics in a city, trading and other activities will not be able to function properly, which will be harmful to the prosperity of the city.