27

Number
$27$ (twenty-seven) is:


 * $3^3$


 * The $3$rd cube number after $1, 8$:
 * $27 = 3 \times 3 \times 3$


 * The smallest odd cube number after $1$:
 * $27 = 3 \times 3 \times 3$


 * The only cube number which is $2$ greater than a square:
 * $27 = 5^2 + 2$


 * The $7$th powerful number after $1, 4, 8, 9, 16, 25$


 * The second of the only known pair of consecutive odd powerful numbers, the other being $25$:
 * $25 = 5^2, 27 = 3^3$


 * Equal to the sum of the digits of its cube:
 * $27^3 = 19 \, 683$; $1 + 9 + 6 + 8 + 3 = 27$


 * The smallest integer which has a reciprocal whose period is $3$:
 * $\dfrac 1 {27} = 0 \cdotp \dot 03 \dot 7$


 * The smallest positive integer which is $3$ times the sum of its digits:
 * $27 = 3 \times \left({2 + 7}\right)$


 * The smallest positive integer which is the sum of $3$ squares in $2$ ways:
 * $27 = 3^2 + 3^2 + 3^2 = 5^2 + 1^2 + 1^2$


 * The $16$th after $1, 2, 4, 5, 6, 8, 9, 12, 13, 15, 16, 17, 20, 24, 25$ of the $24$ positive integers which cannot be expressed as the sum of distinct non-pythagorean primes.

Also see

 * Consecutive Odd Powerful Numbers
 * Square which is 2 Less than Cube
 * Positive Integers Equal to Sum of Digits of Cube
 * Period of Reciprocal of 27 is Smallest with Length 3