9901

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Number

$9901$ (nine thousand, nine hundred and one) is:

The $1221$st prime number

The $3$rd integer after $91$, $9079$ whose square has a decimal representation consisting of the concatenation of $2$ consecutive decreasing integers:

$9901^2 = 98 \, 029 \, 801$

The $6$th unique period prime after $3$, $11$, $37$, $101$, $9091$: its period is $12$:

$\dfrac 1 {9901} = 0 \cdotp \dot 00010 \, 09998 \, 9 \dot 9$

The $8$th integer after $91$, $428$, $573$, $727$, $846$, $7810$, $9079$ whose square has a decimal representation consisting of the concatenation of $2$ consecutive integers:

$9901^2 = 98 \, 029 \, 801$

Also see

• Reciprocal of 9901

• Previous  ... Next: Numbers whose Squares have Digits which form Consecutive Integers
• Previous  ... Next: Numbers whose Squares have Digits which form Consecutive Decreasing Integers

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