91
We don't. In spite of the usual attributions, scholars say that all the psalms, including both Psalm 90 and 91, were written during a relatively short period of only two hundred years, beginning with the Babylonian Exile.
97 is prime.
1
91, 97.
All are divisible by 13. The difference is how many times.
91% of 100, which is 91, divided by 91 equals 1.
100-91 = 9
They are: 90 91 92 93 94 95 and 96 which are between the prime numbers of 89 and 97
91/100 = 0.91 or 91%
Psalm 91:2 says. "I will say of the Lord, He is my refuge and my fortress: my God; in Him will I trust."
70, 77, 84, 91 & 98