# 576

This number is a composite.

576 = sigma(5*7*6). Note that 576 is the first multi-digit number with this property. [Firoozbakht]

A square equal to (2 + 3 + 5 + 7 + 11)^{2} - (2^{2} + 3^{2} + 5^{2} + 7^{2} + 11^{2}). It's the only such case for all primes < 2,000,000,000. [Trotter and
De Geest]

576 is the largest known square that divides the concatenation of its prime factors, where the order of its prime factors can be arranged freely, i.e. 576 = 2 * 2 * 2 * 2 * 3 * 2 * 3 * 2, and 576 divides 22223232. [Rivera]

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