Number
11
- Positive
- Odd
- Prime
- 2 digits
11 is an odd 2-digit integer and a prime number. It has 2 divisors and a digital root of 2.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value11
Digit count2
Digit sum2
Digital root2repeated digit sum
PalindromicYesreads the same backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation11
Distinct prime factors111
Number of divisors2
Sum of divisors σ(n)12
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)10integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 112 in total
Arithmetic
Representations
Decimal11
Binary10114 bits
Octal13
HexadecimalB
Base 36B
Roman numeralXI
In wordseleven
Ordinaleleventh
Scientific notation1.1 × 10^1
Engineering notation11
Nearest landmarks
Powers & multiples
11 to the power 2121
11 to the power 31,331
11 to the power 414,641
11 to the power 5161,051
First ten multiples11, 22, 33, 44, 55, 66, 77, 88, 99, 110
Powers of twoBetween 2^3 (8) and 2^4 (16)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 2
Divisible by 4No, remainder 3
Divisible by 5No, remainder 1
Divisible by 6No, remainder 5
Divisible by 7No, remainder 4
Divisible by 8No, remainder 3
Divisible by 9No, remainder 2
Divisible by 10No, remainder 1
Divisible by 11Yes
Divisible by 12No, remainder 11
Divisible by 100No, remainder 11
Collatz (3n + 1) trajectory
Steps to reach 114the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps11 → 34 → 17 → 52 → 26 → 13 → 40 → 20 → 10 → 5 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage1,100%
11% as a decimal0.11
11% of 10011
11% of 1,000110
As a fraction of 10011/100
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