3600

Number
$3600$ (three thousand, six hundred) is:


 * $2^4 \times 3^2 \times 5^2$


 * The $22$nd square number after $1$, $4$, $36$, $121$, $144$, $256$, $\ldots$, $1936$, $2304$, $2704$, $2916$, $3136$ to be the $\sigma$ (sigma) value of some (strictly) positive integer:
 * $3600 = \map \sigma {\cdots}$


 * The $60$th square number after $1$, $4$, $9$, $16$, $25$, $36$, $\ldots$, $2304$, $2401$, $2500$, $2601$, $2704$, $2809$, $2916$, $3025$, $3136$, $3249$, $3364$, $3481$:
 * $3600 = 60 \times 60$


 * The $49$th positive integer which cannot be expressed as the sum of a square and a prime:
 * $1$, $10$, $25$, $34$, $58$, $64$, $85$, $\ldots$, $2209$, $2304$, $2500$, $2809$, $2986$, $3136$, $3364$, $3481$, $3600$, $\ldots$