The disclosure of many secrets of the genetic code was facilitated by the fact that it was carried out on the basis of mathematical analysis of experimental data: the diversity of genes, their structures and genetic codes. New properties of the genetic code are presented and its most important integral characteristics are established. Two groups of such characteristics were distinguished. The first group refers to the integral characteristics for the areas of DNA, where genes are broken down in pairs and all 5 cases of overlap, allowed by the structure of DNA, were investigated. The second group of characteristics refers to the most extended areas of DNA in which there is no genetic overlap. The interrelation of the established integral characteristics in these groups is shown. As a result, a number of previously unknown effects were discovered. It was possible to establish two functions in which all the over-understood codons in mitochondrial genetic codes (human and other organizations) participate, as well as a significant difference in the integral characteristics of such codes compared to the standard code. Other properties of the structure of the genetic code following from the obtained results are also established. The obtained results allowed us to set and solve one of the new breakthrough problems-the calculation of the genetic code. The full version of the solution to this problem was published in this journal in August 2017. Communications mathematical theory of genetic code, briefly presented in the article N. N. Kozlov and T. M. Eneev, The Fundamentals of a Mathematical Theory of GeneticCode. Doklady Mathematics 2017, Volume 95, № 2, pp. 144-146. This work is an extended version of this article. The focus will be on the issues that have received structured mathematical justification. We tried to give the material in a form accessible to a wide range of mathematicians, so the first two introductory paragraphs are given. The task is simplified by the fact that the extended versions of some of the main results were published in a number of articles cited in the list of references. However, it is crucial to present such results in their relationship, because they relate to the mysteries of one and the same mysterious structure-the genetic code. It should be noted that none of these results was found by the author in other publications, both in domestic and in foreign ones. The disclosure of many secrets of the genetic code was facilitated by the fact that it was carried out on the basis of mathematical analysis of experimental data: the diversity of genes, their structures and genetic codes identified by a number of features.