The number 71820

Q: Is 71820 a prime number?

No. 71820 = 2^2 × 3^3 × 5 × 7 × 19, so it is divisible by 2.

71820 is a composite number with 96 divisors. Its prime factorisation is $2^{2}$ × $3^{3}$ × 5 × 7 × 19. Divisors (96): 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 15, 18, 19, 20, 21 … 71820.

Number

Pick any whole number from 1 to 100,000.

71820 = 2^{2} \times 3^{3} \times 5 \times 7 \times 19

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How to work it out

1
What is special about 71820: a Harshad number: divisible by its digit sum 18.
2
71820 is composite. Its prime factorisation is
$71820 = 2^{2} \times 3^{3} \times 5 \times 7 \times 19$
3
The divisors add up to 268800; without 71820 itself that is 196980, so 71820 is abundant (196980 is more than 71820). Euler's totient φ(71820) = 15552 numbers up to 71820 share no factor with it.
4
The digits of 71820 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 50 steps to reach 1.

LaTeX source of the formulas on this page

\[ 71820 = 2^{2} \times 3^{3} \times 5 \times 7 \times 19 \]

71820 at a glance

Property	Value
Type	composite
Number of divisors	96
Sum of divisors	268800
Euler totient φ(n)	15552
Square	5158112400
Cube	370455632568000
Square root	267.992537 (= 6√1995)
Digit sum / digital root	18 / 9
Collatz steps to 1	50
Scientific notation	7.182 × $10^{4}$

71820 in other forms

Form	Value
In words	seventy-one thousand eight hundred and twenty
Binary (base 2)	10001100010001100
Octal (base 8)	214214
Hexadecimal (base 16)	1188C
Base 3	10122112000
As time	71820 seconds = 19 h 57 min 0 s

Is 71820 divisible by 2 to 12?

Divisor	Answer	Rule
2	Yes (71820 ÷ 2 = 35910)	A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8).
3	Yes (71820 ÷ 3 = 23940)	A number is divisible by 3 if the digits add up to a multiple of 3.
4	Yes (71820 ÷ 4 = 17955)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	Yes (71820 ÷ 5 = 14364)	A number is divisible by 5 if the last digit is 0 or 5.
6	Yes (71820 ÷ 6 = 11970)	A number is divisible by 6 if it is divisible by both 2 and 3.
7	Yes (71820 ÷ 7 = 10260)	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	Yes (71820 ÷ 9 = 7980)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	Yes (71820 ÷ 10 = 7182)	A number is divisible by 10 if the last digit is 0.
11	No (remainder 1)	A number is divisible by 11 if the alternating sum of the digits is a multiple of 11.
12	Yes (71820 ÷ 12 = 5985)	A number is divisible by 12 if it is divisible by both 3 and 4.

Questions

Is 71820 a prime number?

No. 71820 = $2^{2}$ × $3^{3}$ × 5 × 7 × 19, so it is divisible by 2.

What are the factors of 71820?

1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 15, 18, 19, 20, 21, 27, 28, 30, 35, 36, 38, 42, 45, 54, 57, 60, 63, 70, 76, 84, 90, 95, 105, 108, 114, 126, 133, 135, 140, 171, 180, 189, 190, 210, 228, 252, 266, 270, 285, 315, 342, 378, 380, 399, 420, 513, 532, 540, 570, 630, 665, 684, 756, 798, 855, 945, 1026, 1140, 1197, 1260, 1330, 1596, 1710, 1890, 1995, 2052, 2394, 2565, 2660, 3420, 3591, 3780, 3990, 4788, 5130, 5985, 7182, 7980, 10260, 11970, 14364, 17955, 23940, 35910, 71820.

What is 71820 in binary?

10001100010001100 (hexadecimal 1188C, octal 214214).

What is the square root of 71820?

About 267.9925, exactly 6√1995.

Is 71820 divisible by 3?

Yes. Its digits add up to 18, a multiple of 3.

What is special about the number 71820?

71820 is a Harshad number: divisible by its digit sum 18.