13. A positive integer has exactly 8 divisors, the sum of its smallest 3 divisors is 15, and one prime factor of this four-digit number minus five times another prime factor equals twice the third prime factor. This number is $\qquad$
【Analysis】It is known that the smallest positive divisor of a positive integer is 1, and its second smallest positive divisor must be a prime number. 
Consider if the second smallest divisor is 2, then the third smallest divisor is 12, meaning this number is a multiple of 12, which clearly contains the divisor 3, so the third smallest divisor cannot be 12, leading to a contradiction.
Consider if the second smallest divisor is 3, then the third smallest divisor is 11, which is consistent.
If the second smallest divisor is 5, then the third smallest divisor is 9, meaning this number is a multiple of 9, which clearly contains the divisor 3, so the second smallest divisor cannot be 5, leading to a contradiction.
If the third smallest divisor is 7, then the third smallest divisor is also 7, which is discarded.
Thus, the smallest three divisors of this positive integer are $1, 3, 11$.
Thus, the third prime factor of this number could be $3 \times 2 + 11 \times 5 = 61$ or $11 \times 2 + 3 \times 5 = 37$.
Thus, this number is $3 \times 11 \times 61 = 2013$ or $3 \times 11 \times 37 = 1221$.