This is pretending that bits don’t have color¹. In one way they don’t, but in another they do.
Is my paper going to get censored or not?
No, but that is not a problem, since that will never happen. There are too many prime numbers for you to accidentally stumble upon that prime number while doing something else. The theoretical possibility that you might is not a problem for the law, which only concerns itself with problems which occurs in practice.
Since "the colour" is the whole context which led to you mentioning the prime number, the answer is "it depends".
In practice you can publish it as a part of mathematical paper on primes. You cannot publish it saying "here's a prime that decoded as X does illegal thing Y".
Anything in-between is gray zone, with the disclaimer that courts don't like "clever" schemes that try mess with the "colour". So if you try to publish a fake mathematical paper to thumb your nose at the illegality of publishing something, the court will be unsympathetic.
It’s essentially the opposite of Aaron Swartz’s famous “Bits are not a bug” writeup.