Make it prime with the smallest suffix Given a positive integer as input, output the smallest positive integer such that appending its digits (in base 10) to the end of the input number will form a prime number.
Examples
1     --&gt;   1
2     --&gt;   3
8     --&gt;   3
9     --&gt;   7
11    --&gt;   3
20    --&gt;  11
43    --&gt;   1
134   --&gt;  11
3492  --&gt;  11
3493  --&gt;   9
65595 --&gt;  19

Rules and Scoring

This is code golf, so shortest code wins
Standard rules and loopholes apply
Use any convenient I/O format
The largest concatenated number (which is larger than both the input and output) your solution supports must be at least \$2^{53} - 1\$. (This is the largest odd integer that can be represented with double precision floats)
Leading zeros should not be added to numbers before appending them to the input number
Primality tests must be exact
Jelly, 7 bytes
1ṭVẒɗ1#

Try it online!
How it works
1ṭVẒɗ1# - Main link. Takes n on the left
    ɗ   - Define a dyad f(k, n) from the previous 3 links:
 ṭ      -   Tack; Yield [n, k]
  V     -   Eval; Smash together into a single integer
   Ẓ    -   Is prime?
1    1# - Starting from k = 1, find the first k such that f(k, n) is true