253

Number
$253$ (two hundred and fifty-three) is:
 * $11 \times 23$


 * The $22$nd triangular number after $1, 3, 6, 10, 15, \ldots, 136, 153, 171, 190, 210, 231$:
 * $253 = \displaystyle \sum_{k \mathop = 1}^{22} k = \dfrac {22 \times \left({22 + 1}\right)} 2$


 * The $15$th integer after $7, 13, 19, 35, 38, 41, 57, 65, 70, 125, 130, 190, 205, 223$ the decimal representation of whose square can be split into two parts which are each themselves square:
 * $253^2 = 64 \, 009; 6400 = 80^2, 9 = 3^2$