**Is 21 an abundant number?** Examples. The first 28 abundant numbers are: 12, 18, 20, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, … (sequence A005101 in the OEIS). For example, the proper divisors of 24 are 1, 2, 3, 4, 6, 8, and 12, whose sum is 36.

## What is Coprime number?

Co-prime numbers are **the numbers whose common factor is only 1**. There should be a minimum of two numbers to form a set of co-prime numbers. Such numbers have only 1 as their highest common factor, for example, {4 and 7}, {5, 7, 9} are co-prime numbers.

## What is the perfect number?

Perfect number, **a positive integer that is equal to the sum of its proper divisors**. The smallest perfect number is 6, which is the sum of 1, 2, and 3. Other perfect numbers are 28, 496, and 8,128.

## Is 17 abundant deficient or perfect?

The Integers 1 to 100

N | Divisors of N | Notes |
---|---|---|

17 | 1, 17 | Deficient |

18 | 1, 2, 3, 6, 9, 18 | Abundant |

19 | 1, 19 | Deficient |

20 | 1, 2, 4, 5, 10, 20 | Abundant |

## Is 51 a Harshad number?

The harshad numbers in base 12 are: 1, 2, 3, 4, 5, 6, 7, 8, 9, ᘔ, Ɛ, 10, 1ᘔ, 20, 29, 30, 38, 40, 47, 50, 56, 60, 65, 70, 74, 80, 83, 90, 92, ᘔ0, ᘔ1, Ɛ0, 100, 10ᘔ, 110, 115, 119, 120, 122, 128, 130, 134, 137, 146, 150, 153, 155, 164, 172, 173, 182, 191, 1ᘔ0, 1Ɛ0, 1Ɛᘔ, 200, …

## Is 7 and 15 Coprime numbers?

By the definition of coprime numbers, if the given set of numbers have 1 as an only common factor then the given set of numbers will be coprime numbers. **Factors of 7 are 1 and 7**. Factors of 15 are 1, 3, 5 and 15. . since there is only one common factor the given numbers are co-prime.

## Is 12 and 15 Coprime numbers?

So, by this definition, 15 and 8 are co-prime, but 15 and 9 are not. There are 4 positive integers less than 12 and **co- prime with 12**. They are 1, 5, 7, and 11. There are 8 positive integers less than 15 and co- prime with 15.

## Are 18 and 35 Coprime numbers?

Coprime numbers are numbers that have only 1 as their HCF. 18 and **35 have no common factors**, Therefore, 18 and 35 are coprime numbers.

## Why is 7 the perfect number?

Seven is **the number of completeness and perfection** (both physical and spiritual). It derives much of its meaning from being tied directly to God’s creation of all things. … The word ‘created’ is used 7 times describing God’s creative work (Genesis 1:1, 21, 27 three times; 2:3; 2:4).

## Why Is 9 the perfect number?

9 is **the only positive perfect power** that is one more than another positive perfect power, by Mihăilescu’s Theorem. 9 is the highest single-digit number in the decimal system. It is the second non-unitary square prime of the form (p^{2}) and the first that is odd. All subsequent squares of this form are odd.

## Why is 28 a perfect number?

A number is perfect if all of its factors, including 1 but excluding itself, perfectly add up to the number you began with. 6, for example, is perfect, because its factors — 3, 2, and 1 — all sum up to 6. 28 is perfect too: 14, 7, 4, 2, and 1 **add up** to 28.

## Is 160 a deficient number?

Is 160 a deficient number? No, **160 is not a deficient number**: to be deficient, 160 should have been such that 160 is larger than the sum of its proper divisors, i.e., the divisors of 160 without 160 itself (that is 1 + 2 + 4 + 5 + 8 + 10 + 16 + 20 + 32 + 40 + 80 = 218). … The smallest abundant number is 12.

## Is 32 a deficient number?

A perfect number is an integer that equals the sum of its proper divisors. For example, 24 is abundant, its divisors giving a sum of 36; **32 is deficient**, giving a sum…

## Why is 11 a deficient number?

Its proper divisors are 1, 3 and 7, and their sum is 11. Because 11 **is less than 21**, the number 21 is deficient.

## Why is 6174 a magic number?

6174 is known as **Kaprekar’s constant** after the Indian mathematician D. R. Kaprekar. This number is notable for the following rule: … Arrange the digits in descending and then in ascending order to get two four-digit numbers, adding leading zeros if necessary.

## Is 0 A Niven number?

For mathematicians the answer is easy: **zero is an even number**. … Because any number that can be divided by two to create another whole number is even.

## What is the Krishnamurthy number?

A Krishnamurthy number is **a number whose sum of the factorial of digits is equal to the number itself**. For example 145, 1! + 4!

## Are 2 and 3 coprime numbers?

Any two prime numbers are **co-prime** to each other: As every prime number has only two factors 1 and the number itself, the only common factor of two prime numbers will be 1. For example, 2 and 3 are two prime numbers. … The only common factor is 1 and hence they are co-prime.

## Is 15 a coprime number?

Factors of 15 are 1, 3, 5 and 15. The common factor of 14 and 15 is only 1. So, **14 and 15 are coprime numbers**.

## Are 9 and 10 coprime numbers?

9 and 10 are the coprime numbers .

## Is 18 and 23 a coprime number?

18 and 23 are **coprime integers** as they don’t have any common factor other than 1.

## Is 17 and 68 is Coprime number?

**17 and 68 are not co-prime** because 1 is not the only common factor of these numbers. Example, 17 is another common factor of 17 and 68.

## Are 12 and 18 Coprime numbers Why?

yes, **they are co-prime numbers because only one factor is common that is 1**. … factors of 68: 1,2,4,17,34,68. v) 216 and 215. factors of 216: 1,2,3,4,6,8,9,12,18,24,27,36,54,72,102,216.

## Is 31 and 93 a Coprime?

The factors of 31 are 1 and 31 and the factors of 93 are 1, 3 and 31. Here 31 and 93 have two common factors: they are **1 and 31**. Hence, their HCF is 31 and they are not co-prime.

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