The number 77900

Q: Is 77900 a prime number?

No. 77900 = 2^2 × 5^2 × 19 × 41, so it is divisible by 2.

77900 is a composite number with 36 divisors. Its prime factorisation is $2^{2}$ × $5^{2}$ × 19 × 41. Divisors (36): 1, 2, 4, 5, 10, 19, 20, 25, 38, 41, 50, 76, 82, 95, 100, 164 … 77900.

Number

Pick any whole number from 1 to 100,000.

77900 = 2^{2} \times 5^{2} \times 19 \times 41

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How to work it out

1
77900 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
2
77900 is composite. Its prime factorisation is
$77900 = 2^{2} \times 5^{2} \times 19 \times 41$
3
The divisors add up to 182280; without 77900 itself that is 104380, so 77900 is abundant (104380 is more than 77900). Euler's totient φ(77900) = 28800 numbers up to 77900 share no factor with it.
4
The digits of 77900 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 169 steps to reach 1.

LaTeX source of the formulas on this page

\[ 77900 = 2^{2} \times 5^{2} \times 19 \times 41 \]

77900 at a glance

Property	Value
Type	composite
Number of divisors	36
Sum of divisors	182280
Euler totient φ(n)	28800
Square	6068410000
Cube	472729139000000
Square root	279.105715 (= 10√779)
Digit sum / digital root	23 / 5
Collatz steps to 1	169
Scientific notation	7.79 × $10^{4}$

77900 in other forms

Form	Value
In words	seventy-seven thousand nine hundred
Binary (base 2)	10011000001001100
Octal (base 8)	230114
Hexadecimal (base 16)	1304C
Base 3	10221212012
As time	77900 seconds = 21 h 38 min 20 s

Is 77900 divisible by 2 to 12?

Divisor	Answer	Rule
2	Yes (77900 ÷ 2 = 38950)	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 (77900 ÷ 4 = 19475)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	Yes (77900 ÷ 5 = 15580)	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	No (remainder 4)	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 5)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	Yes (77900 ÷ 10 = 7790)	A number is divisible by 10 if the last digit is 0.
11	No (remainder 9)	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 77900 a prime number?

No. 77900 = $2^{2}$ × $5^{2}$ × 19 × 41, so it is divisible by 2.

What are the factors of 77900?

1, 2, 4, 5, 10, 19, 20, 25, 38, 41, 50, 76, 82, 95, 100, 164, 190, 205, 380, 410, 475, 779, 820, 950, 1025, 1558, 1900, 2050, 3116, 3895, 4100, 7790, 15580, 19475, 38950, 77900.

What is 77900 in binary?

10011000001001100 (hexadecimal 1304C, octal 230114).

What is the square root of 77900?

About 279.1057, exactly 10√779.

Is 77900 divisible by 3?

No. Its digits add up to 23, which is not a multiple of 3.

What is special about the number 77900?

It is a composite number with 36 divisors.