Oh honey, 861 is about as composite as a Kardashian selfie. It can be divided by 1, 3, 7, 17, 21, 51, 119, and 357. So, unless you're looking for a Prime number to make your day, 861 is definitely not it.
Yes
yes
4, composite. 67, prime.
Prime
1 is special 2 prime 3 prime 4 composite 5 prime 6 composite 7 prime 8 composite 9 composite 10 composite 11 prime 12 composite ext.
It is composite.
The prime factorization of 861 is 3 x 7 x 41
Yes
yes
yes
neither prime or composite
It is prime
It would be impossible to list them all, since numbers go on forever, but here are some of them: 2 - Prime 3 - Prime 4 - Composite 5 - Prime 6 - Composite 7 - Prime 8 - Composite 9 - Composite 10 - Composite 11 - Prime 12 - Composite 13 - Prime 14 - Composite 15 - Composite 16 - Composite 17 - Prime 18 - Composite 19 - Prime 20 - Composite 21 - Composite 22 - Composite 23 - Prime 24 - Composite 25 - Composite 26 - Composite 27 - Composite 28 - Composite 29 - Prime 30 - Composite 31 - Prime 32 - Composite 33 - Composite 34 - Composite 35 - Composite 36 - Composite 37 - Prime 38 - Composite 39 - Composite 40 - Composite 41 - Prime 42 - Composite 43 - Prime 44 - Composite 45 - Composite 46 - Composite 47 - Prime 48 - Composite 49 - Composite 50 - Composite
4, composite. 67, prime.
Prime
1 is special 2 prime 3 prime 4 composite 5 prime 6 composite 7 prime 8 composite 9 composite 10 composite 11 prime 12 composite ext.
5 prime, 25 composite.