非互补欧拉商数（noncototient）是指一个正整数n，不存在任一个整数m使下式成立：

其中表示欧拉函数，是小于m的正整数中和m互质整数的个数，称为m的互补欧拉商数，因此非互补欧拉商数就是指不在互补欧拉商数值域内的整数。

头几个非互补欧拉商数是：

10, 26, 34, 50, 52, 58, 86, 100, 116, 122, 130, 134, 146, 154, 170, 172, 186, 202, 206, 218, 222, 232, 244, 260, 266, 268, 274, 290, 292, 298, 310, 326, 340, 344, 346, 362, 366, 372, 386, 394, 404, 412, 436, 466, 470, 474, 482, 490, 518, 520 （OEIS中的数列A005278）。

In mathematics, a noncototient is a positive integer n that cannot be expressed as the difference between a positive integer m and the number of coprime integers below it. That is, m − φ(m) = n, where φ stands for Euler's totient function, has no solution for m. The cototient of n is defined as n − φ(n), so a noncototient is a number that is never a cototient.