I notice that $T^2=S^1\times S^1$ can be embedded in $\mathbb{R}^3$ as a hypersurface (submnaifolds of codimension 1).
In general,
(1). could the product of spheres $S^{m_1}\times\cdots\times S^{m_n}$ be embedded in Euclidean space as a hypersurface?
(2). could $T^n=\prod_n S^{1}$ be embedded in Euclidean space as a hypersurface?
(3). could $S^m\times S^n$ be embedded in Euclidean space as a hypersurface?