9, 81, 6561, 43046721, ...This would be the sequence 9^(2^(n-1))
17 factors.
43046721
43046721=3^16. The factors are 3^0 through 3^16: 1, 3, 9, 27, 81, 243, 729, 2187, 6561, 19683, 59049, 177147, 531441, 1594323, 4782969, 14348907, 43046721
9 to the eighth power = 43046721
square of 6561 is 43046721 square root is 81
Divisors are used to divide numbers.
9-8 = 1/98 = 1/43046721
2,4,8 (1 and 16 are divisors too, but the number and 1 are always divisors)
Sum of divisors: 1728.
Sum of divisors: 980.
Sum of divisors = 91.