11. (5 points) A pile of pearls totals 6468, if each time a prime number of pearls is taken, after several times it is exactly finished, there are $a$ different ways; if each time an odd number of pearls is taken, after several times it is exactly finished, there are $b$ different ways, then $a+b=$ $\qquad$ (each time the number of pearls taken is the same)
【Solution】Solution: $6468=2 \times 2 \times 3 \times 7 \times 7 \times 11$.
From this, we know that the prime numbers among the factors of 6468 are $2, 3, 7, 11$.
Thus, if each time a prime number of items is taken, and after several times they are all taken, there are 4 different ways to do so.
Also, $3 \times 7=21, 3 \times 7 \times 7=147, 7 \times 7=49, 7 \times 7 \times 11=539, 3 \times 7 \times 7 \times 11=1617$,
Thus, if each time an odd number of items is taken, and after several times they are all taken, there are 9 different ways to do so: each time taking 1, 3, 7, 11, 21, 49, 147, 539, 1617 items respectively.

Thus, $a+b=4+9=13$.
The answer is: 13.