Find the largest $ 85$-digit integer which has property: the sum of its digits equals to the product of its digits.
To find the largest 85-digit integer such that the sum of its digits equals the product of its digits, we need to consider the properties of digits and their sums and products. Let's denote the 85-digit number as \( a_1a_2a_3 \ldots a_{85} \).

1. **Initial Considerations**:
   - The sum of the digits \( S = a_1 + a_2 + \cdots + a_{85} \).
   - The product of the digits \( P = a_1 \cdot a_2 \cdot \cdots \cdot a_{85} \).
   - We need \( S = P \).

2. **Maximizing the Number**:
   - To maximize the number, we should use the largest possible digits while ensuring \( S = P \).
   - Using digits like 9 or 8 will quickly increase the product, making it difficult to balance with the sum.

3. **Using Smaller Digits**:
   - Using smaller digits like 1, 2, 3, etc., helps in balancing the sum and product.
   - The digit 1 is particularly useful because it does not change the product but contributes to the sum.

4. **Constructing the Number**:
   - Let's start with the largest digits and then fill the rest with 1s.
   - Consider the digits 8, 3, 2, and 2. Their sum is \( 8 + 3 + 2 + 2 = 15 \) and their product is \( 8 \cdot 3 \cdot 2 \cdot 2 = 96 \).
   - To balance the sum and product, we need to add 81 ones. This gives us:
     \[
     S = 8 + 3 + 2 + 2 + 81 \cdot 1 = 96
     \]
     \[
     P = 8 \cdot 3 \cdot 2 \cdot 2 \cdot 1^{81} = 96
     \]

5. **Verification**:
   - The number \( 8322\underbrace{111 \cdots 1}_{81 \text{ ones}} \) has 85 digits.
   - The sum of the digits is \( 8 + 3 + 2 + 2 + 81 = 96 \).
   - The product of the digits is \( 8 \cdot 3 \cdot 2 \cdot 2 \cdot 1^{81} = 96 \).

Thus, the largest 85-digit integer with the property that the sum of its digits equals the product of its digits is \( 8322\underbrace{111 \cdots 1}_{81 \text{ ones}} \).

The final answer is \( \boxed{8322\underbrace{111 \cdots 1}_{81 \text{ ones}}} \).