Number
7
- Positive
- Odd
- Prime
- 1 digit
7 is an odd 1-digit integer and a prime number. It has 2 divisors and a digital root of 7.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value7
Digit count1
Digit sum7
Digital root7repeated digit sum
PalindromicYesreads the same backwards
Happy numberYessquared-digit sums reach 1
Harshad numberYesdivisible by its own digit sum
Armstrong numberYesdigits raised to the digit count sum to itself
Factors & divisors
Prime factorisation7
Distinct prime factors17
Number of divisors2
Sum of divisors σ(n)8
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)6integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 72 in total
Arithmetic
Representations
Decimal7
Binary1113 bits
Octal7
Hexadecimal7
Base 367
Roman numeralVII
In wordsseven
Ordinalseventh
Scientific notation7 × 10^0
Engineering notation7
Nearest landmarks
Powers & multiples
7 to the power 249
7 to the power 3343
7 to the power 42,401
7 to the power 516,807
First ten multiples7, 14, 21, 28, 35, 42, 49, 56, 63, 70
Powers of twoBetween 2^2 (4) and 2^3 (8)
Divisibility tests
Divisible by 2No, remainder 1
Divisible by 3No, remainder 1
Divisible by 4No, remainder 3
Divisible by 5No, remainder 2
Divisible by 6No, remainder 1
Divisible by 7Yes
Divisible by 8No, remainder 7
Divisible by 9No, remainder 7
Divisible by 10No, remainder 7
Divisible by 11No, remainder 7
Divisible by 12No, remainder 7
Divisible by 100No, remainder 7
Collatz (3n + 1) trajectory
Steps to reach 116the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps7 → 22 → 11 → 34 → 17 → 52 → 26 → 13 → 40 → 20 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage700%
7% as a decimal0.07
7% of 1007
7% of 1,00070
As a fraction of 1007/100
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Derived from 7
Other readings
Also reads as
U+0037 (unicode character)
- U+0037
- 7
- Decimal digit
U+0037 is code point 55 (7), a decimal digit in the Basic Latin (ASCII) block of the Basic Multilingual Plane. It takes 1 byte in UTF-8 and 1 unit in UTF-16.
Identity
Code pointU+0037
Decimal55
Character7
General categoryDecimal digit
BlockBasic Latin (ASCII)
PlaneBasic Multilingual Planeplane 0
Official nameNot includedthe Unicode Character Database is not bundled; a stale copy would be worse than none
Encodings
UTF-8371 byte
UTF-160037a single unit
UTF-3200000037
Binary110111
Bytes in UTF-8 vs UTF-161 vs 2UTF-16 is not always smaller, even for non-Latin text
Writing it in code
HTML numeric entity7
HTML hex entity7
CSS escape\0037
JavaScript\u0037
Python\u0037
Percent-encoded (URL)%37
Things that catch people out
JavaScript string length1
Needs a surrogate pairNo
Safe in a URL unescapedYes
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