The decimal 840 Number in the Braille Alphabet is
Número = Number sign. Means that it opens a number instead of a sequence of letters.
All natural divisors of 840 are:
1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420, 840
And that is the number factored 840 = 2 x 2 x 2 x 3 x 5 x 7 (it is not prime)