Algebraic numbers

https://www.wikiwand.com/en/Algebraic_number

An algebraic number is any complex number that is a root of a non-zero polynomial (that is, a value which causes the polynomial to equal zero) in one variable with rational coefficients (or equivalently, by clearing denominators, with integer coefficients).

All integers and rational numbers are algebraic, as are all roots of integers. The same is not true for all real numbers or all complex numbers.

Those real and complex numbers which are not algebraic are called transcendental numbers. They include π and e.

While the set of complex numbers is uncountable, the set of algebraic numbers is countable and has measure zero in the Lebesgue measure as a subset of the complex numbers, and in this sense almost all complex numbers are transcendental.