3940

Number
$3940$ (three thousand, nine hundred and forty) is:
 * $2^2 \times 5 \times 197$


 * The $40$th heptagonal number after $1, 7, 18, 34, 55, 81, 112, \ldots, 2205, 2356, 2512, 2673, 2839, 3010, 3186, 3367, 3553, 3744$:
 * $3940 = \displaystyle \sum_{k \mathop = 1}^{40} \left({5 k - 4}\right) = \dfrac {40 \left({5 \times 40 - 3}\right)} 2$