十六元数透过实数形成16维的矢量空间。彷如八元数,其乘法不符合交换律及结合律。然而，与八元数不一样，十六元数甚至不符合交错性。尽管如此，十六元数仍然符合幂结合性。

十六元数的16个单元十六元数是: 1, e₁, e₂, e₃, e₄, e₅, e₆, e₇, e₈, e₉, e₁₀, e₁₁, e₁₂, e₁₃, e₁₄ 及 e₁₅,

单元乘数表如下:

In abstract algebra, the sedenions form a 16-dimensional noncommutative and nonassociative algebra over the reals obtained by applying the Cayley–Dickson construction to the octonions. The set of sedenions is denoted by .

The term "sedenion" is also used for other 16-dimensional algebraic structures, such as a tensor product of 2 copies of the biquaternions, or the algebra of 4 by 4 matrices over the reals, or that studied by Smith (1995).