204

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Number

$204$ (two hundred and four) is:

$2^2 \times 3 \times 17$

The $3$rd positive integer after $200$, $202$ that cannot be made into a prime number by changing just $1$ digit

The $8$th square pyramidal number after $1$, $5$, $14$, $30$, $55$, $91$, $140$:

$204 = 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 = \ds \sum_{k \mathop = 1}^8 k^2 = \dfrac {8 \paren {8 + 1} \paren {2 \times 8 + 1} } 6$

The $40$th positive integer $n$ such that no factorial of an integer can end with $n$ zeroes.

Also see

• Sum of Cubes of 3 Consecutive Integers which is Square

• Previous  ... Next: Square Pyramidal Number
• Previous  ... Next: Numbers of Zeroes that Factorial does not end with
• Previous  ... Next: Numbers that cannot be made Prime by changing 1 Digit

Sources

• 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $204$
• 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $204$