2420

Number
$2420$ (two thousand, four hundred and twenty) is:
 * $2^2 \times 5 \times 11^2$


 * The $40$th second pentagonal number after $2$, $7$, $15$, $26$, $\ldots$, $1751$, $1855$, $1962$, $2072$, $2185$, $2301$:
 * $2420 = \dfrac {40 \paren {3 \times 40 + 1} } 2$


 * The $80$th generalized pentagonal number after $1$, $2$, $5$, $7$, $12$, $15$, $\ldots$, $2072$, $2147$, $2185$, $2262$, $2301$, $2380$:
 * $2420 = \dfrac {40 \paren {3 \times 40 + 1} } 2$