Number
71
- Positive
- Odd
- Prime
- 2 digits
71 is an odd 2-digit integer and a prime number. It has 2 divisors and a digital root of 8.
Number properties
ParityOddnot divisible by 2
SignPositive
PrimalityPrime
Absolute value71
Digit count2
Digit sum8
Digital root8repeated digit sum
PalindromicNoreads differently backwards
Happy numberNosquared-digit sums reach 1
Harshad numberNodivisible by its own digit sum
Factors & divisors
Prime factorisation71
Distinct prime factors171
Number of divisors2
Sum of divisors σ(n)72
Aliquot sum1sum of the proper divisors
ClassificationDeficientthe aliquot sum is less than the number
Euler's totient φ(n)70integers below n that share no factor with it
SquarefreeYesno repeated prime factor
All divisors1, 712 in total
Arithmetic
Representations
Decimal71
Binary10001117 bits
Octal107
Hexadecimal47
Base 361Z
Roman numeralLXXI
In wordsseventy-one
Ordinalseventy-first
Scientific notation7.1 × 10^1
Engineering notation71
Nearest landmarks
Powers & multiples
71 to the power 25,041
71 to the power 3357,911
71 to the power 425,411,681
71 to the power 51,804,229,351
First ten multiples71, 142, 213, 284, 355, 426, 497, 568, 639, 710
Powers of twoBetween 2^6 (64) and 2^7 (128)
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 1
Divisible by 8No, remainder 7
Divisible by 9No, remainder 8
Divisible by 10No, remainder 1
Divisible by 11No, remainder 5
Divisible by 12No, remainder 11
Divisible by 100No, remainder 71
Collatz (3n + 1) trajectory
Steps to reach 1102the total stopping time
Reaches 1Yesthe Collatz conjecture says every positive integer does, but it is unproven
First steps71 → 214 → 107 → 322 → 161 → 484 → 242 → 121 → 364 → 182 → …
Last steps… → 5 → 16 → 8 → 4 → 2 → 1
As a percentage & fraction
As a percentage7,100%
71% as a decimal0.71
71% of 10071
71% of 1,000710
As a fraction of 10071/100
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