4027

This number is a prime.

The only prime permutation of the digits of the smallest composite Mersenne number 2^p - 1 with p prime, i.e., 2047.

4027^5 = 3301^5 + 3169^5 + 3037^5 + 2411^5 + 1481^5 + 859^5 + 569^5. Note that all base numbers and exponents are prime. Found by Takao Nakamura. [Meller]

The sum of the first 4027 triangular numbers (10892237654) is the smallest pandigital sum of the first n triangular numbers. [Gaydos]