Abstract We present new results about the factorization of $\Phi_p(M) \in \mathbb{F}_2[x]$, where $p$ is a prime number,
$\Phi_p$ is the corresponding cyclotomic polynomial, and $M$ is a Mersenne prime polynomial. In particular,
these results improve our understanding of the factorization of the sum of the divisors of $M^{2h}$ for a positive integer $h$.
This is related to the fixed points of the sum of divisors function $\sigma$ on $\mathbb{F}_2[x]$.
The factorization of composed polynomials over finite fields is not well understood,
and classical results on cyclotomic polynomials primarily concern the special case where $M$ is replaced by $x$. 
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