The letters are in combinations of one to five letters and come from a pool of 14 letters. The letters heading the initialled chapters, such as the A, the L and the M, in chapter 2 when counted in the text of the chapter and added together will give a total divisible by 19. This is true of all 29 initialled chapters in the Quran. The significance of this is twofold. Second, it demonstrates that the Quran is of divine origin since it is impossible to deliberately compose It in this manner.
Words have specific meanings and can only be manipulated to a minor extent.
Unless one is prepared to tack words with the designated letters, regardless of their meaning, together to get the number of letters required, it is impossible to deliberately compose the text to end up with the requisite number of letters and still retain a lucid meaning. An attempt to compose any text to contain a designated number of letters, the sum of which is a multiple of any specific number, will quickly demonstrate its impossibility. The first revelation of the Quran was the first five verses of chapter 96, Al-'Alaq. These five verses consist of 19 words and 76 letters. Chapter 96 consists of 19 verses and 304 letters.