Arithmetics
The Quran turned out to have a
unique signature.
 The "Basmala
بِسْمِ
اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ" consists of 19 letters.

"Basmala" appears 114 times in the Quran, a multiple of 19.

The count of chapters in the Quran is a multiple of 19.

The sum of chapters' numbers in the Quran is a multiple of
19.
 The sum of all digits mentioned in the Quran is a multiple of 19.
 The count of the word "Allah" in all the Quran is a multiple of 19.
 The sum of all verse numbers in which the word "Allah" appears is a multiple of 19.
 Some chapters start with letters that have no meaning at all. When we
count the number of occurrences of all the letters in the
Quran and give each letter a numeric value equal to its rank
and then add the numeric values of those letters we get a multiple of 19.
The most used letter is (ا) and we give it a
value of 1. The second most used letter is (ل) and we give it
a value of 2... Then we add the numeric value of those letters
we get a multiple of 19 (361=19x19). So if anyone changed a single word containing those letters in the Quran the signature would have been broken.
(YouTube in Arabic.)
God says that He assigned 19 angels to guard Hell, and He made their count "19" so that believers shall increase their faith.
(In the Christian Bible
Jesus insists that the only sign we should verify is him
being in the grave for three days and three nights (Matthew 12:3840). So we
are checking: He was crucified on Friday afternoon,
the day before the Sabbath (Mark 15:42)
and then he was resurrected on Sunday morning
(Mark 16:9). Between Friday afternoon and Sunday morning
there is 36 hours. Can anyone fit within those 36 hours three days and three nights?)