69

Number
$69$ (sixty-nine) is:
 * $3 \times 23$


 * The $24$th semiprime:
 * $69 = 3 \times 23$


 * The $20$th Ulam number after $1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 26, 28, 36, 38, 47, 48, 53, 57, 62$:
 * $69 = 16 + 53$


 * The $4$th after $21, 29, 61$ of the $5$ $2$-digit positive integers which can occur as a $5$-fold repetition at the end of a square number


 * The only integer whose square and cube use each of the digits from $0$ to $9$ exactly once each:
 * $69^2 = 4761$, $69^3 = 328 \, 509$

Also see

 * Number whose Square and Cube use all Digits Once