  Let $A$ be a square-free abelian variety defined over a number field $K$. Let
$S$ be a density one set of prime ideals $\mathfrak{p}$ of $\mathcal{O}_K$. A
famous theorem of Faltings says that the Frobenius polynomials
$P_{A,\mathfrak{p}}(x)$ for $\mathfrak{p}\in S$ determine $A$ up to isogeny. We
show that the prime factors of
$|A(\mathbb{F}_{\mathfrak{p}})|=P_{A,\mathfrak{p}}(1)$ for $\mathfrak{p}\in S$
also determine $A$ up to isogeny over an explicit finite extension of $K$. The
proof relies on understanding the $\ell$-adic monodromy groups which come from
the $\ell$-adic Galois representations of $A$, and the absolute Weyl group
action on their weights.

Number Theory