989898989

This number is a prime.

The smallest smoothly undulating palindromic prime formed from digits 8 and 9. Note the square prime digits and the cubic prime digits. Replacing the square prime digits by their square roots, we have the palindromic prime: 383838383. Replacing the cubic prime digits by their cubic roots, we have the palindromic prime: 929292929. Replacing both the prime squares and prime cubes by their respective roots, we have the smoothly undulating palindromic prime formed from the prime digits 2 and 3: 323232323. [Silva]