The number 81340

Q: Is 81340 a prime number?

No. 81340 = 2^2 × 5 × 7^2 × 83, so it is divisible by 2.

81340 is a composite number with 36 divisors. Its prime factorisation is $2^{2}$ × 5 × $7^{2}$ × 83. Divisors (36): 1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 49, 70, 83, 98, 140, 166 … 81340.

Number

Pick any whole number from 1 to 100,000.

81340 = 2^{2} \times 5 \times 7^{2} \times 83

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How to work it out

1
81340 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
2
81340 is composite. Its prime factorisation is
$81340 = 2^{2} \times 5 \times 7^{2} \times 83$
3
The divisors add up to 201096; without 81340 itself that is 119756, so 81340 is abundant (119756 is more than 81340). Euler's totient φ(81340) = 27552 numbers up to 81340 share no factor with it.
4
The digits of 81340 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 182 steps to reach 1.

LaTeX source of the formulas on this page

\[ 81340 = 2^{2} \times 5 \times 7^{2} \times 83 \]

81340 at a glance

Property	Value
Type	composite
Number of divisors	36
Sum of divisors	201096
Euler totient φ(n)	27552
Square	6616195600
Cube	538161350104000
Square root	285.201683 (= 14√415)
Digit sum / digital root	16 / 7
Collatz steps to 1	182
Scientific notation	8.134 × $10^{4}$

81340 in other forms

Form	Value
In words	eighty-one thousand three hundred and forty
Binary (base 2)	10011110110111100
Octal (base 8)	236674
Hexadecimal (base 16)	13DBC
Base 3	11010120121
As time	81340 seconds = 22 h 35 min 40 s

Is 81340 divisible by 2 to 12?

Divisor	Answer	Rule
2	Yes (81340 ÷ 2 = 40670)	A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8).
3	No (remainder 1)	A number is divisible by 3 if the digits add up to a multiple of 3.
4	Yes (81340 ÷ 4 = 20335)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	Yes (81340 ÷ 5 = 16268)	A number is divisible by 5 if the last digit is 0 or 5.
6	No (remainder 4)	A number is divisible by 6 if it is divisible by both 2 and 3.
7	Yes (81340 ÷ 7 = 11620)	A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7.
8	No (remainder 4)	A number is divisible by 8 if the last three digits make a multiple of 8.
9	No (remainder 7)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	Yes (81340 ÷ 10 = 8134)	A number is divisible by 10 if the last digit is 0.
11	No (remainder 6)	A number is divisible by 11 if the alternating sum of the digits is a multiple of 11.
12	No (remainder 4)	A number is divisible by 12 if it is divisible by both 3 and 4.

Questions

Is 81340 a prime number?

No. 81340 = $2^{2}$ × 5 × $7^{2}$ × 83, so it is divisible by 2.

What are the factors of 81340?

1, 2, 4, 5, 7, 10, 14, 20, 28, 35, 49, 70, 83, 98, 140, 166, 196, 245, 332, 415, 490, 581, 830, 980, 1162, 1660, 2324, 2905, 4067, 5810, 8134, 11620, 16268, 20335, 40670, 81340.

What is 81340 in binary?

10011110110111100 (hexadecimal 13DBC, octal 236674).

What is the square root of 81340?

About 285.2017, exactly 14√415.

Is 81340 divisible by 3?

No. Its digits add up to 16, which is not a multiple of 3.

What is special about the number 81340?

It is a composite number with 36 divisors.