In his treatise Die Grundlagen der Arithmetik, Gottlob Frege tries to find a definition of a number. First, he rejects the idea that the number could be a property of external (empirical) objects. Then he comes with a suggestion that a numerical statement expresses a property of a concept, namely it indicates how many objects fall under the concept. Subsequently Frege rejects, or at least essentially modifies, also this definition, because in his view a number cannot be a property - it should be an object. The article tries to show that Frege's first definition of number seems to be, despite his own opinion, much more promising than he supposed. It also argues that Frege's argumentation against the (possibly) empirical character of number is by no means convincing.