正规数 (整数)

一个400以内正规数其约数关系的哈斯图，其纵向为对数尺度

正规数（Regular numbers）是指可以整除60的乘幂的整数，也就是60乘幂的约数，例如60² = 3600 = 48 × 75，48和75都可以整除60的平方，也都是正规数。

在许多数学及应用的领域会用到60乘幂的约数，在不同的领域中其名称也有所不同。

• 在数论中，60乘幂的约数也称为5-光滑数，因为其素因数只有2,3或是5，这是k-光滑数中的一个特例，k-光滑数是指其素因数都小于等于k的整数。
• 在巴比伦数学中，60乘幂的约数称为正规数或是60正规数，因为巴比伦数学是使用六十进制，因此这类数字格外的重要。
• 在计算机科学，60乘幂的约数称为汉明数（Hamming numbers），得名自数学家理查德·卫斯里·汉明，他提出一个用电脑依序找出60乘幂的约数的算法。

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