The number 28028

Q: Is 28028 a prime number?

No. 28028 = 2^2 × 7^2 × 11 × 13, so it is divisible by 2.

28028 is a composite number with 36 divisors. Its prime factorisation is $2^{2}$ × $7^{2}$ × 11 × 13. Divisors (36): 1, 2, 4, 7, 11, 13, 14, 22, 26, 28, 44, 49, 52, 77, 91, 98 … 28028.

Number

Pick any whole number from 1 to 100,000.

28028 = 2^{2} \times 7^{2} \times 11 \times 13

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How to work it out

1
28028 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
2
28028 is composite. Its prime factorisation is
$28028 = 2^{2} \times 7^{2} \times 11 \times 13$
3
The divisors add up to 67032; without 28028 itself that is 39004, so 28028 is abundant (39004 is more than 28028). Euler's totient φ(28028) = 10080 numbers up to 28028 share no factor with it.
4
The digits of 28028 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 90 steps to reach 1.

LaTeX source of the formulas on this page

\[ 28028 = 2^{2} \times 7^{2} \times 11 \times 13 \]

28028 at a glance

Property	Value
Type	composite
Number of divisors	36
Sum of divisors	67032
Euler totient φ(n)	10080
Square	785568784
Cube	22017921877952
Square root	167.415650 (= 14√143)
Digit sum / digital root	20 / 2
Collatz steps to 1	90
Scientific notation	2.8028 × $10^{4}$

28028 in other forms

Form	Value
In words	twenty-eight thousand and twenty-eight
Binary (base 2)	110110101111100
Octal (base 8)	66574
Hexadecimal (base 16)	6D7C
Base 3	1102110002
As time	28028 seconds = 7 h 47 min 8 s

Is 28028 divisible by 2 to 12?

Divisor	Answer	Rule
2	Yes (28028 ÷ 2 = 14014)	A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8).
3	No (remainder 2)	A number is divisible by 3 if the digits add up to a multiple of 3.
4	Yes (28028 ÷ 4 = 7007)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	No (remainder 3)	A number is divisible by 5 if the last digit is 0 or 5.
6	No (remainder 2)	A number is divisible by 6 if it is divisible by both 2 and 3.
7	Yes (28028 ÷ 7 = 4004)	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 2)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	No (remainder 8)	A number is divisible by 10 if the last digit is 0.
11	Yes (28028 ÷ 11 = 2548)	A number is divisible by 11 if the alternating sum of the digits is a multiple of 11.
12	No (remainder 8)	A number is divisible by 12 if it is divisible by both 3 and 4.

Questions

Is 28028 a prime number?

No. 28028 = $2^{2}$ × $7^{2}$ × 11 × 13, so it is divisible by 2.

What are the factors of 28028?

1, 2, 4, 7, 11, 13, 14, 22, 26, 28, 44, 49, 52, 77, 91, 98, 143, 154, 182, 196, 286, 308, 364, 539, 572, 637, 1001, 1078, 1274, 2002, 2156, 2548, 4004, 7007, 14014, 28028.

What is 28028 in binary?

110110101111100 (hexadecimal 6D7C, octal 66574).

What is the square root of 28028?

About 167.4157, exactly 14√143.

Is 28028 divisible by 3?

No. Its digits add up to 20, which is not a multiple of 3.

What is special about the number 28028?

It is a composite number with 36 divisors.