Prime numbers - with the exception of 2 - are particularily "masculine", in that as well as being odd, they are highly independent (i.e. have no factors). 

Now psychologically, the prime structures (i.e. primitive impulses), are particularily "feminine" (i.e. pure instinctive response rather than reason). Thus the "masculine" prime numbers (quantities) complement the "feminine" prime number structures (qualities). 

The first prime number "2" which is even and "feminine", has a special significance. I shall refer to this as the root prime number. Psychologically, it is related very closely to the fundamental symbol of the unconscious i.e. 0. As we have seen 0 arises from the dynamic (negative) counterbalancing of the (positive) 1. Mathematically this can be statically expressed as 1 - 1 = 0. Thus, whereas the (quantitative) mathematical interpretation of 0 is static, the the corresponding psychological interpretation of 0 - which is qualitative - is dynamic, involving complementary opposite poles. 

Now 2 is just a mathematically reduced interpretation of this dynamic relationship. When each pole is experienced separately it is positive. (It is only in complementary dynamic relationship that the positive-negative polarity arises). Thus when the conscious linear approach is used to (statically) express the inherently dynamic unconscious, it appears as 2. There are - in static terms - two poles involved in terms of this relationship. 

The dynamic 0 (unconsciously), then in terms of conscious interpretation is 2. 

Therefore we can accurately say that conscious process itself is fundamentally one dimensional, and the unconscious process fundamentally two dimensional (in static terms). 

2 which is the reduced interpretation of 0, carries the same unconscious (intuitive) connotations. Not surprisingly, as intuition is a defining characteristic of the feminine principle, 2 in most cultures is seen as a "feminine" number. By extension all even numbers (which are divisible by 2) are similarily treated as "feminine" numbers. By the same reasoning all odd numbers (which are not divisible by 2), are treated as "masculine". Indeed the prime numbers (excluding 2) which are all odd comprise a special subset of the odd "masculine" numbers. Having no factors they are highly "independent" and thereby carry the psychological connotation of being especially masculine.