Brachylog, 77 6 bytes
ṗ⊇ubṗsĖṗ⊇uṗsȮ
How it works
ṗ⊇ubṗsĖṗ⊇uṗsȮ the implicit input
ṗ is a prime
⊇u and from every unique subset
b without the input itself
ṗs select the primes
ĖȮ and this should be an emptya listSlower but simpler alternative, 7 bytes
⊇uṗs[?]
⊇u from the unique subsets
ṗs select all primes
with [?]one andelement (the result is just theprime input in a listitself)
Brachylog, 7 bytes
ṗ⊇ubṗsĖ
How it works
ṗ⊇ubṗsĖ the implicit input
ṗ is a prime
⊇u and from every unique subset
b without the input itself
ṗs select the primes
Ė and this should be an empty listSlower but simpler alternative, 7 bytes
⊇uṗs[?]
⊇u from the unique subsets
ṗs select all primes
[?] and the result is just the input in a list
Brachylog, 7 6 bytes
ṗ⊇uṗsȮ
ṗ⊇uṗsȮ the implicit input
ṗ is a prime
⊇u and from every unique subset
ṗs select the primes
Ȯ and this should be a list with one element (the prime input itself)
Brachylog, 7 bytes
ṗ⊇ubṗsĖ
How it works
ṗ⊇ubṗsĖ the implicit input
ṗ is a prime
⊇u and from every unique subset
b without the input itself
ṗs select the primes
Ė and this should be an empty list
Slower but simpler alternative, 7 bytes
⊇uṗs[?]
⊇u from the unique subsets
ṗs select all primes
[?] and the result is just the input in a list
Brachylog, 7 bytes
ṗ⊇ubṗsĖ
How it works
ṗ⊇ubṗsĖ the implicit input
ṗ is a prime
⊇u and from every unique subset
b without the input itself
ṗs select the primes
Ė and this should be an empty list
Brachylog, 7 bytes
ṗ⊇ubṗsĖ
How it works
ṗ⊇ubṗsĖ the implicit input
ṗ is a prime
⊇u and from every unique subset
b without the input itself
ṗs select the primes
Ė and this should be an empty list
Slower but simpler alternative, 7 bytes
⊇uṗs[?]
⊇u from the unique subsets
ṗs select all primes
[?] and the result is just the input in a list