The number 21372
21372 is a composite number with 24 divisors. Its prime factorisation is × 3 × 13 × 137. Divisors (24): 1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78, 137, 156, 274, 411, 548 … 21372.
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How to work it out
- 1
21372 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21372 is composite. Its prime factorisation is
- 3
The divisors add up to 54096; without 21372 itself that is 32724, so 21372 is abundant (32724 is more than 21372). Euler's totient φ(21372) = 6528 numbers up to 21372 share no factor with it.
- 4
The digits of 21372 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21372 = 2^{2} \times 3 \times 13 \times 137 \]21372 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 54096 |
| Euler totient φ(n) | 6528 |
| Square | 456762384 |
| Cube | 9761925670848 |
| Square root | 146.191655 (= 2√5343) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1372 × |
21372 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and seventy-two |
| Binary (base 2) | 101001101111100 |
| Octal (base 8) | 51574 |
| Hexadecimal (base 16) | 537C |
| Base 3 | 1002022120 |
| As time | 21372 seconds = 5 h 56 min 12 s |
Is 21372 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21372 ÷ 2 = 10686) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21372 ÷ 3 = 7124) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21372 ÷ 4 = 5343) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (21372 ÷ 6 = 3562) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 2) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21372 ÷ 12 = 1781) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21372 a prime number?
No. 21372 = × 3 × 13 × 137, so it is divisible by 2.
What are the factors of 21372?
1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78, 137, 156, 274, 411, 548, 822, 1644, 1781, 3562, 5343, 7124, 10686, 21372.
What is 21372 in binary?
101001101111100 (hexadecimal 537C, octal 51574).
What is the square root of 21372?
About 146.1917, exactly 2√5343.
Is 21372 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 21372?
It is a composite number with 24 divisors.