Smallest multiplier that reveals a factor of a semiprime
05AB1E, 18 16 15 bytes

-2 bytes thanks to Riley!

-1 byte thanks to Emigna!

[N¹*b¹Ñ¦¨båOiNq


Explanation:

[                   # Infinite loop start
 N                  # Push the amount of times we have iterated
  ¹*               # Multiplied by input
    b              # Convert to binary
     ¹Ñ¦¨b         # Calculate the proper divisors of the input in binary excluding one
          åO       # Check if a substring of N * m in binary is in the divisors
            iNq    # If so, print how many times we have iterated and terminate the program


Try it online!