One millionth is equal to 0.000 001, or 1 x 10−6 in scientific notation.
It is the reciprocal of a million, and can be also written as 1⁄1,000,000.
[1] Units using this fraction can be indicated using the prefix "micro-" from Greek, meaning "small".
[2] Numbers of this quantity are expressed in terms of μ (the Greek letter mu).
[3] "Millionth" can also mean the ordinal number that comes after the nine hundred, ninety-nine thousand, nine hundred, ninety-ninth and before the million and first.