# Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

## Unique Properties of 524

- 524 is the smallest nonpalindrome such that its largest two proper divisors, and only them, are nontrivial palindromes (have more than one digit) (The divisors of 524 are 1, 2, 4, 131, 262, 524)

## Common Properties of 524

A positive integer greater than 1 that is not prime is called *composite*.

Composite numbers are opposite to prime numbers.

The number n is *deficient* if the sum of all its positive divisors except itself is less than n.

Compare with perfect and abundant numbers.

A number is *even* if it is divisible by 2.

Numbers that are not even are odd. Compare with another pair -- evil and odious numbers.

The number n is *odious* if it has an odd number of 1's in its binary expansion.

Guess what evil numbers are.

The next *Ulam* number is uniquely the sum of two earlier distinct Ulam numbers.