4200

Number
$4200$ (four thousand two hundred) is:


 * $2^3 \times 3 \times 5^2 \times 7$


 * The $20$th pentagonal pyramidal number after $1, 6, 12, 40, 75, 126, 196, 288, 405, 550, 726, 936, 1183, 1470, 1800, 2176, 2601, 3078, 3610$:
 * $4200 = \displaystyle \sum_{k \mathop = 1}^{20} \dfrac {k \left({3 k - 1}\right)} 2 = \dfrac {20^2 \left({20 + 1}\right)} 2$