125 (one hundred [and] twenty-five) is the natural number following 124 and preceding 126.
125 is the cube of 5. It can be expressed as a sum of two squares in two different ways, 125 = 10ò + 5ò = 11ò + 2ò.
125 and 126 form a Ruth-Aaron pair under the second definition in which repeated prime factors are counted as often as they occur.
Like many other powers of 5, it is a Friedman number in base 10 since 125 = 5<sup>1 + 2</sup>.
125 is the center of a close triplet of perfect powers, (121 = 11<sup>2</sup>, 125 = 5<sup>3</sup>, 128 = 2<sup>7</sup>). Excluding the trivial cases of 0 and 1, the only closer such triplet is (4,8,9) and the only other equally close is (25, 27, 32).
The 125th anniversary of an event is celebrated as the quasquicentennial.