How many zero divisors does a ring have?

Question

How can I calculate the number of zero divisors in the ring $$\mathbb Z /n\mathbb Z$$ for $n = 1.000.000$?

Welcome to Mathematics Stack Exchange. Are you familiar with Euler's totient function? — J. W. Tanner, Jun 01 '20 at 20:25

score 1 · Accepted Answer · answered Jun 01 '20 at 20:29

1

Hint:

Can you calculate the number of units in the ring $\mathbb Z/1000000\mathbb Z$?

answered Jun 01 '20 at 20:29

J. W. Tanner

1 Answers1