27571 is a number without the digit 0 with two distinct prime factors such that n + SOD(n) and n + POD(n) both have two distinct prime factors. Here the semiprimes are:

27571 + 22 = 27593 = 41 * 673

27571 + 490 = 28061 = 11 * 2551

The sequence from 27571 up to 40000 is:

27571, 27578, 27598, 27635, 27641, 27649, 27757, 27842, 27849, 27899, 27933, 27934, 28141, 28187, 28235, 28293, 28321, 28345, 28369, 28498, 28529, 28769, 28783, 28811, 28846, 28874, 28963, 29219, 29227, 29263, 29278, 29291, 29335, 29377, 29485, 29487, 29534, 29543, 29553, 29593, 29594, 29617, 29626, 29657, 29765, 29773, 29797, 29951, 31187, 31273, 31435, 31439, 31462, 31618, 31619, 31631, 31677, 31693, 31754, 31762, 31767, 31783, 31826, 31874, 31893, 32161, 32177, 32179, 32221, 32449, 32521, 32527, 32534, 32551, 32629, 32666, 32735, 32755, 32819, 32827, 32845, 32863, 32881, 33121, 33133, 33431, 33458, 33499, 33523, 33526, 33643, 33658, 33659, 33671, 33729, 33837, 33842, 33877, 33926, 33947, 33963, 33983, 34315, 34321, 34363, 34467, 34514, 34531, 34555, 34634, 34733, 34754, 34829, 34837, 34873, 34966, 34973, 34993, 35138, 35218, 35219, 35233, 35318, 35366, 35414, 35477, 35522, 35611, 35614, 35633, 35657, 35678, 35693, 35726, 35761, 35782, 35789, 35813, 35857, 35887, 35927, 36111, 36154, 36169, 36178, 36193, 36227, 36289, 36398, 36447, 36463, 36485, 36535, 36577, 36641, 36733, 36759, 36853, 36893, 36961, 37165, 37239, 37381, 37486, 37586, 37615, 37678, 37787, 37837, 37865, 37943, 37981, 38137, 38179, 38243, 38245, 38297, 38359, 38422, 38429, 38463, 38473, 38489, 38515, 38549, 38615, 38758, 38771, 38837, 38849, 38854, 38914, 38926, 38957, 38978, 38983, 38999, 39127, 39145, 39257, 39413, 39453, 39481, 39637, 39661, 39723, 39747, 39811, 39871, 39917, 39941, 39959

27571 is a cyclic and Duffinian number.

27571 can be rendered as a digit equation as follows:

-2 | (7 + 5) + 7 = 1