Is 180 a prime number?
It is possible to find out using mathematical methods whether a given integer is a prime number or not.
For 180, the answer is: No, 180 is not a prime number.
The list of all positive divisors (i.e., the list of all integers that divide 180) is as follows: 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 60, 90, 180.
For 180 to be a prime number, it would have been required that 180 has only two divisors, i.e., itself and 1.
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Actually, one can immediately see that 180 cannot be prime, because 5 is one of its divisors: indeed, a number ending with 0 or 5 has necessarily 5 among its divisors. The last digit of 180 is 0, so it is divisible by 5 and is therefore not prime.
As a consequence:
- 180 is a multiple of 1
- 180 is a multiple of 2
- 180 is a multiple of 3
- 180 is a multiple of 4
- 180 is a multiple of 5
- 180 is a multiple of 6
- 180 is a multiple of 9
- 180 is a multiple of 10
- 180 is a multiple of 12
- 180 is a multiple of 15
- 180 is a multiple of 18
- 180 is a multiple of 20
- 180 is a multiple of 30
- 180 is a multiple of 36
- 180 is a multiple of 45
- 180 is a multiple of 60
- 180 is a multiple of 90
For 180 to be a prime number, it would have been required that 180 has only two divisors, i.e., itself and 1.
Is 180 a deficient number?
No, 180 is not a deficient number: to be deficient, 180 should have been such that 180 is larger than the sum of its proper divisors, i.e., the divisors of 180 without 180 itself (that is 1 + 2 + 3 + 4 + 5 + 6 + 9 + 10 + 12 + 15 + 18 + 20 + 30 + 36 + 45 + 60 + 90 = 366).
In fact, 180 is an abundant number; 180 is strictly smaller than the sum of its proper divisors (that is 1 + 2 + 3 + 4 + 5 + 6 + 9 + 10 + 12 + 15 + 18 + 20 + 30 + 36 + 45 + 60 + 90 = 366). The smallest abundant number is 12.