65. For each natural number from 1 to 2018, write out the product of its digits (for example: the product of the digits of the single-digit number 5 is 5; the product of the digits of the two-digit number 72 is $7 \times 2=14$; the product of the digits of the three-digit number 607 is $6 \times 0 \times 7=0$, etc.). Then the sum of these 2018 products is $\qquad$
Reference answer: 184320