As a person
Born on the 13th, or a 13/4 life path: discipline, routine, law and order.
As a day
The 13th, or a 13/4 day, is a 4 day: routine and detail work.
People get pulled over on the 4th, 13th and 31st. Follow the rules.
As a year
A 13/4 year is a 4 year: work, routine and rules.
Friends and enemies
As a 4. Friends: 6, the best match in numerology, then 8 and 9.
As a 4. Enemies: 3 and 5.
Compounds
1+3 = 4, so 13 reads as a 4. Every 4 line applies to it.
The 1 leads the 3, and together they reduce to 4. Flip it and you get 31, the 4 that talks.