9. (10 points) The natural number 2015 can be expressed as the sum of $\qquad$ consecutive odd numbers.

Expressing the above text in English, please retain the original text's line breaks and format, and output the translation result directly.
【Analysis】First, decompose 2015 into prime factors, $2015=5 \times 13 \times 31$. The sum of multiple consecutive odd numbers is a multiple of the middle number; if 5, 13, 31 are taken as the middle number, the condition cannot be met; only when $5 \times 13=65$ is taken as the middle number, from $35, 37, 39 \cdots 95$, there are exactly 31 numbers, and the sum is 2015; therefore, 2015 can be expressed as the sum of at most 31 consecutive odd numbers.

【Solution】Solution: $2015=5 \times 13 \times 31$;
The sum of multiple consecutive odd numbers is a multiple of the middle number;
If 5, 13, 31 are taken as the middle number, the condition cannot be met;
Only when $5 \times 13=65$ is taken as the middle number, from $35, 37, 39 \cdots 95$, there are exactly 31 numbers, and the sum is 2015;

Therefore, 2015 can be expressed as the sum of at most 31 consecutive odd numbers.
The answer is: 31.