The number 87720

Q: Is 87720 a prime number?

No. 87720 = 2^3 × 3 × 5 × 17 × 43, so it is divisible by 2.

87720 is a composite number with 64 divisors. Its prime factorisation is $2^{3}$ × 3 × 5 × 17 × 43. Divisors (64): 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 30, 34, 40 … 87720.

Number

Pick any whole number from 1 to 100,000.

87720 = 2^{3} \times 3 \times 5 \times 17 \times 43

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How to work it out

1
What is special about 87720: a Harshad number: divisible by its digit sum 24.
2
87720 is composite. Its prime factorisation is
$87720 = 2^{3} \times 3 \times 5 \times 17 \times 43$
3
The divisors add up to 285120; without 87720 itself that is 197400, so 87720 is abundant (197400 is more than 87720). Euler's totient φ(87720) = 21504 numbers up to 87720 share no factor with it.
4
The digits of 87720 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 133 steps to reach 1.

LaTeX source of the formulas on this page

\[ 87720 = 2^{3} \times 3 \times 5 \times 17 \times 43 \]

87720 at a glance

Property	Value
Type	composite
Number of divisors	64
Sum of divisors	285120
Euler totient φ(n)	21504
Square	7694798400
Cube	674987715648000
Square root	296.175624 (= 2√21930)
Digit sum / digital root	24 / 6
Collatz steps to 1	133
Scientific notation	8.772 × $10^{4}$

87720 in other forms

Form	Value
In words	eighty-seven thousand seven hundred and twenty
Binary (base 2)	10101011010101000
Octal (base 8)	253250
Hexadecimal (base 16)	156A8
Base 3	11110022220
As time	87720 seconds = 24 h 22 min 0 s

Is 87720 divisible by 2 to 12?

Divisor	Answer	Rule
2	Yes (87720 ÷ 2 = 43860)	A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8).
3	Yes (87720 ÷ 3 = 29240)	A number is divisible by 3 if the digits add up to a multiple of 3.
4	Yes (87720 ÷ 4 = 21930)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	Yes (87720 ÷ 5 = 17544)	A number is divisible by 5 if the last digit is 0 or 5.
6	Yes (87720 ÷ 6 = 14620)	A number is divisible by 6 if it is divisible by both 2 and 3.
7	No (remainder 3)	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	Yes (87720 ÷ 8 = 10965)	A number is divisible by 8 if the last three digits make a multiple of 8.
9	No (remainder 6)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	Yes (87720 ÷ 10 = 8772)	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	Yes (87720 ÷ 12 = 7310)	A number is divisible by 12 if it is divisible by both 3 and 4.

Questions

Is 87720 a prime number?

No. 87720 = $2^{3}$ × 3 × 5 × 17 × 43, so it is divisible by 2.

What are the factors of 87720?

1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 30, 34, 40, 43, 51, 60, 68, 85, 86, 102, 120, 129, 136, 170, 172, 204, 215, 255, 258, 340, 344, 408, 430, 510, 516, 645, 680, 731, 860, 1020, 1032, 1290, 1462, 1720, 2040, 2193, 2580, 2924, 3655, 4386, 5160, 5848, 7310, 8772, 10965, 14620, 17544, 21930, 29240, 43860, 87720.

What is 87720 in binary?

10101011010101000 (hexadecimal 156A8, octal 253250).

What is the square root of 87720?

About 296.1756, exactly 2√21930.

Is 87720 divisible by 3?

Yes. Its digits add up to 24, a multiple of 3.

What is special about the number 87720?

87720 is a Harshad number: divisible by its digit sum 24.