Does having a number in your domain name negatively affect SEO?

Some companies prefer letters over numbers. The biggest example that I can think of is Three, who redirects to the letter vanity name (exception is Denmark).

www.3.ie --> www.three.ie

www.3.se --> www.tre.se

www.3.co.uk --> (doesn't exist, only www.three.co.uk)

www.3.dk --> www.3.dk

www.3.it --> (doesn't exist, only www.tre.it)