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The result must be divisible by 3. Using the example above: 16,499,205,854,376 has four of the digits 1, 4 and 7 and four of the digits 2, 5 and 8; since 4 − 4 = 0 is a multiple of 3, the number 16,499,205,854,376 is divisible by 3. Subtracting 2 times the last digit from the rest gives a multiple of 3. (Works because 21 is divisible by 3)
For example, 3 is a divisor of 21, since 21/7 = 3 (and therefore 7 is also a divisor of 21). If m is a divisor of n , then so is − m . The tables below only list positive divisors.
616 is a member of the Padovan sequence, coming after 265, 351, 465 (it is the sum of the first two of these). [3] 616 is a polygonal number in four different ways: it is a heptagonal number, as well as 13-, 31- and 104-gonal.
A natural number is divisible by three if the sum of its digits in base 10 is divisible by 3. For example, the number 21 is divisible by three (3 times 7) and the sum of its digits is 2 + 1 = 3. Because of this, the reverse of any number that is divisible by three (or indeed, any permutation of its digits) is also divisible by three. For ...
Digit sums and digital roots can be used for quick divisibility tests: a natural number is divisible by 3 or 9 if and only if its digit sum (or digital root) is divisible by 3 or 9, respectively. For divisibility by 9, this test is called the rule of nines and is the basis of the casting out nines technique for checking calculations.
The only base-4 repunit prime is 5 (). = (+) (), and 3 always divides + when n is odd and when n is even. For n greater than 2, both + and are greater than 3, so removing the factor of 3 still leaves two factors greater than 1.
232,792,560 = superior highly composite number; [22] colossally abundant number; [23] smallest number divisible by the numbers from 1 to 22 (there is no smaller number divisible by the numbers from 1 to 20 since any number divisible by 3 and 7 must be divisible by 21 and any number divisible by 2 and 11 must be divisible by 22)
360 is divisible by the number of its divisors , and it is the smallest number divisible by every natural number from 1 to 10, except 7. Furthermore, one of the divisors of 360 is 72, which is the number of primes below it. 360 is the sum of twin primes (179 + 181) and the sum of four consecutive powers of three (9 + 27 + 81 + 243).