528
This number is a composite.
The smallest non-palindromic number whose sum of divisors is the same as the sum of divisors of its reverse, i.e., Sigma(528) = Sigma(825). [Gupta]
The smallest zeroless triangular numbers t such that t+1
and t-1 are semiprime. [Bajpai]
528 and 534 are the smallest pair of consecutive multiples
of 6 for which neither is adjacent to a prime number. [Gaydos]
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