What is the multiplicative of 26?

The term "multiplicative of 26" isn't standard, but if you mean the multiples of 26, they are the results of multiplying 26 by integers. For example, the first few multiples of 26 are 26 (1x26), 52 (2x26), 78 (3x26), and so on. In general, the multiples can be expressed as 26n, where n is any integer.