Is 985 a prime number?

It is possible to find out using mathematical methods whether a given integer is a prime number or not.

For 985, the answer is: No, 985 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 985) is as follows: 1, 5, 197, 985.

For 985 to be a prime number, it would have been required that 985 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

Actually, one can immediately see that 985 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 985 is 5, so it is divisible by 5 and is therefore not prime.

As a consequence:

985 is a multiple of 1
985 is a multiple of 5
985 is a multiple of 197

For 985 to be a prime number, it would have been required that 985 has only two divisors, i.e., itself and 1.

However, 985 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 985 = 5 x 197, where 5 and 197 are both prime numbers.

Is 985 a deficient number?

Yes, 985 is a deficient number, that is to say 985 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 985 without 985 itself (that is 1 + 5 + 197 = 203).

Parity of 985

985 is an odd number, because it is not evenly divisible by 2.

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What is an even number?

Is 985 a perfect square number?

A number is a perfect square (or a square number) if its square root is an integer; that is to say, it is the product of an integer with itself. Here, the square root of 985 is about 31.385.

Thus, the square root of 985 is not an integer, and therefore 985 is not a square number.

What is the square number of 985?

The square of a number (here 985) is the result of the product of this number (985) by itself (i.e., 985 × 985); the square of 985 is sometimes called "raising 985 to the power 2", or "985 squared".

The square of 985 is 970 225 because 985 × 985 = 985² = 970 225.

As a consequence, 985 is the square root of 970 225.

Number of digits of 985

985 is a number with 3 digits.

What are the multiples of 985?

The multiples of 985 are all integers evenly divisible by 985, that is all numbers such that the remainder of the division by 985 is zero. There are infinitely many multiples of 985. The smallest multiples of 985 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 985 too, since 0 × 985 = 0
985: indeed, 985 is a multiple of itself, since 985 is evenly divisible by 985 (we have 985 / 985 = 1, so the remainder of this division is indeed zero)
1 970: indeed, 1 970 = 985 × 2
2 955: indeed, 2 955 = 985 × 3
3 940: indeed, 3 940 = 985 × 4
4 925: indeed, 4 925 = 985 × 5
etc.

How to determine whether an integer is a prime number?

To determine the primality of a number, several algorithms can be used. The most naive technique is to test all divisors strictly smaller to the number of which we want to determine the primality (here 985). First, we can eliminate all even numbers greater than 2 (and hence 4, 6, 8…). Then, we can stop this check when we reach the square root of the number of which we want to determine the primality (here the square root is about 31.385). Historically, the sieve of Eratosthenes (dating from the Greek mathematics) implements this technique in a relatively efficient manner.

More modern techniques include the sieve of Atkin, probabilistic algorithms, and the cyclotomic AKS test.

Numbers near 985

Preceding numbers: …983, 984
Following numbers: 986, 987…

Nearest numbers from 985

Preceding prime number: 983
Following prime number: 991