27539 is a member of OEIS A056212: primes p whose period of reciprocal equals (p-1)/7. There are 30 such primes in the range up to 40000. The sequence can be generated as follows:
INPUT
divisor=7
L=[]
for p in prime_range(40000):
if (1/p).period()==(p-1)/divisor:
L.append(p)
print(L)
print(len(L))
OUTPUT
[211, 617, 1499, 2087, 2857, 6007, 6469, 7127, 7211, 7589, 9661, 10193, 13259, 13553, 14771, 18047, 18257, 19937, 20903, 21379, 23549, 26153, 27259, 27539, 32299, 33181, 33461, 34847, 35491, 35897]
30
The relative numbers for various divisors is shown below. For a list of divisors from 1 to 100 in the range 2 to 100,000, follow this permalink.
Divisor Number
1 1588
2 1180
3 287
4 309
5 86
6 201
7 30
8 63
9 35
10 52
11 14
12 49
13 10
14 32
15 13
16 19
17 4
18 35
19 5
20 8
21 13
22 5
23 1
24 9
25 5
26 7
27 2
28 6
29 1
30 11
31 0
27539 is a Sophie Germain and a twin prime with 27541.
27539 cannot be rendered as a digit equation:
*NO_EQUATION*