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When it comes to the rest of the code, [...) builds a list of bool values and x[...)1 gets the index of the first truthy element.

• First of all, we get the all the possible combinations of 2 digits (number_of_digits / 2). We get ['12', '16', '10', '26', '20', '60'].

• Then, we get the possible permutations of each, [['12', '21'], ['16', '61'], ['10', '01'], ['26', '62'], ['20', '02'], ['60', '06']].

• We flatten that (['12', '21', '16', '61', '10', '01', '26', '62', '20', '02', '60', '06']) and get all the possible 2-element combinations. This list is quite long:

    [['12', '21'], ['12', '16'], ['12', '61'], ['12', '10'], ['12', '01'], ['12', '26'], ['12', '62'], ['12', '20'], ['12', '02'], ['12', '60'], ['12', '06'], ['21', '16'], ['21', '61'], ['21', '10'], ['21', '01'], ['21', '26'], ['21', '62'], ['21', '20'], ['21', '02'], ['21', '60'], ['21', '06'], ['16', '61'], ['16', '10'], ['16', '01'], ['16', '26'], ['16', '62'], ['16', '20'], ['16', '02'], ['16', '60'], ['16', '06'], ['61', '10'], ['61', '01'], ['61', '26'], ['61', '62'], ['61', '20'], ['61', '02'], ['61', '60'], ['61', '06'], ['10', '01'], ['10', '26'], ['10', '62'], ['10', '20'], ['10', '02'], ['10', '60'], ['10', '06'], ['01', '26'], ['01', '62'], ['01', '20'], ['01', '02'], ['01', '60'], ['01', '06'], ['26', '62'], ['26', '20'], ['26', '02'], ['26', '60'], ['26', '06'], ['62', '20'], ['62', '02'], ['62', '60'], ['62', '06'], ['20', '02'], ['20', '60'], ['20', '06'], ['02', '60'], ['02', '06'], ['60', '06']]
  

• The next step is getting the product of each pair:

    [252, 192, 732, 120, 12, 312, 744, 240, 24, 720, 72, 336, 1281, 210, 21, 546, 1302, 420, 42, 1260, 126, 976, 160, 16, 416, 992, 320, 32, 960, 96, 610, 61, 1586, 3782, 1220, 122, 3660, 366, 10, 260, 620, 200, 20, 600, 60, 26, 62, 20, 2, 60, 6, 1612, 520, 52, 1560, 156, 1240, 124, 3720, 372, 40, 1200, 120, 120, 12, 360]
  

• And then compare to the input:

    [False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False]
  

• Finally, the last step is checking if any value is truthy. And there is one ( at index 19 into the list). Hence, this returns a truthy value for 1260, thanks to the pair [21, 60].

qsP{*MyPQQ

q        Q   Is equal to the input?
 s           The sum of:
   {*MyPQ    Its divisors,
  P          Popped (since we want the proper divisors).

• First of all, we get the all the possible combinations of 2 digits (number_of_digits / 2). We get ['12', '16', '10', '26', '20', '60'].

• Then, we get the possible permutations of each, [['12', '21'], ['16', '61'], ['10', '01'], ['26', '62'], ['20', '02'], ['60', '06']].

• We flatten that (['12', '21', '16', '61', '10', '01', '26', '62', '20', '02', '60', '06']) and get all the possible 2-element combinations. This list is quite long:

    [['12', '21'], ['12', '16'], ['12', '61'], ['12', '10'], ['12', '01'], ['12', '26'], ['12', '62'], ['12', '20'], ['12', '02'], ['12', '60'], ['12', '06'], ['21', '16'], ['21', '61'], ['21', '10'], ['21', '01'], ['21', '26'], ['21', '62'], ['21', '20'], ['21', '02'], ['21', '60'], ['21', '06'], ['16', '61'], ['16', '10'], ['16', '01'], ['16', '26'], ['16', '62'], ['16', '20'], ['16', '02'], ['16', '60'], ['16', '06'], ['61', '10'], ['61', '01'], ['61', '26'], ['61', '62'], ['61', '20'], ['61', '02'], ['61', '60'], ['61', '06'], ['10', '01'], ['10', '26'], ['10', '62'], ['10', '20'], ['10', '02'], ['10', '60'], ['10', '06'], ['01', '26'], ['01', '62'], ['01', '20'], ['01', '02'], ['01', '60'], ['01', '06'], ['26', '62'], ['26', '20'], ['26', '02'], ['26', '60'], ['26', '06'], ['62', '20'], ['62', '02'], ['62', '60'], ['62', '06'], ['20', '02'], ['20', '60'], ['20', '06'], ['02', '60'], ['02', '06'], ['60', '06']]
  

• The next step is getting the product of each pair:

    [252, 192, 732, 120, 12, 312, 744, 240, 24, 720, 72, 336, 1281, 210, 21, 546, 1302, 420, 42, 1260, 126, 976, 160, 16, 416, 992, 320, 32, 960, 96, 610, 61, 1586, 3782, 1220, 122, 3660, 366, 10, 260, 620, 200, 20, 600, 60, 26, 62, 20, 2, 60, 6, 1612, 520, 52, 1560, 156, 1240, 124, 3720, 372, 40, 1200, 120, 120, 12, 360]
  

• And then compare to the input:

    [False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, True, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False, False]
  

• Finally, the last step is checking if any value is truthy. And there is one (at index 19 into the list). Hence, this returns a truthy value for 1260, thanks to the pair [21, 60].

qsP{*MyPQQ

q        Q   Is equal to the input?
 s           Sum.
   {*MyPQ    Its divisors.
  P          Popped (since we want the proper divisors).

&.AjQ2P_Q

   jQ2      The input in binary as a list of digits.
 .A         Are all truthy (i.e equal to 1)?
&     P_Q   Is Prime?

qQsm^sdlKK

q            Is equal?
 Q           The Input
   m^sdlKK   Each of its digits raised to the power of the length
  s          Summed.

&.AjQ2P_Q

   jQ2      The input in binary as a list of digits.
 .A         Are all truthy (i.e equal to 1)?
&     P_Q   ... And is prime?

qQsm^sdlKK

q            Is equal?
 Q           The Input
   m     K   Map over the string representation of the input.
    ^sdlK    Raise each digit to the power of the number of digits the input has.
  s          Summed.