The number 42025

No. 42025 = 5^2 × 41^2, so it is divisible by 5.

42025 is a perfect square (205²). Its prime factorisation is $5^{2}$ × $41^{2}$ . Divisors (9): 1, 5, 25, 41, 205, 1025, 1681, 8405, 42025.

Number

Pick any whole number from 1 to 100,000.

42025 = 5^{2} \times 41^{2}

How to work it out

1
What is special about 42025: a perfect square (205²); a happy number: repeatedly adding the squares of its digits reaches 1.
2
42025 is composite. Its prime factorisation is
$42025 = 5^{2} \times 41^{2}$
3
The divisors add up to 53413; without 42025 itself that is 11388, so 42025 is deficient (11388 is less than 42025). Euler's totient φ(42025) = 32800 numbers up to 42025 share no factor with it.
4
The digits of 42025 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 132 steps to reach 1.

LaTeX source of the formulas on this page

\[ 42025 = 5^{2} \times 41^{2} \]

Form	Value
In words	forty-two thousand and twenty-five
Binary (base 2)	1010010000101001
Octal (base 8)	122051
Hexadecimal (base 16)	A429
Base 3	2010122111
As time	42025 seconds = 11 h 40 min 25 s

Divisor	Answer	Rule
2	No (remainder 1)	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	No (remainder 1)	A number is divisible by 4 if the last two digits make a multiple of 4.
5	Yes (42025 ÷ 5 = 8405)	A number is divisible by 5 if the last digit is 0 or 5.
6	No (remainder 1)	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 1)	A number is divisible by 8 if the last three digits make a multiple of 8.
9	No (remainder 4)	A number is divisible by 9 if the digits add up to a multiple of 9.
10	No (remainder 5)	A number is divisible by 10 if the last digit is 0.
11	No (remainder 5)	A number is divisible by 11 if the alternating sum of the digits is a multiple of 11.
12	No (remainder 1)	A number is divisible by 12 if it is divisible by both 3 and 4.

Is 42025 a prime number?

No. 42025 = $5^{2}$ × $41^{2}$ , so it is divisible by 5.

What are the factors of 42025?

1, 5, 25, 41, 205, 1025, 1681, 8405, 42025.

What is 42025 in binary?

1010010000101001 (hexadecimal A429, octal 122051).

What is the square root of 42025?

205, because 205 × 205 = 42025.

Is 42025 divisible by 3?

No. Its digits add up to 13, which is not a multiple of 3.

What is special about the number 42025?

42025 is a perfect square (205²); a happy number: repeatedly adding the squares of its digits reaches 1.