Is 842 a prime number?

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

For 842, the answer is: No, 842 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 842) is as follows: 1, 2, 421, 842.

For 842 to be a prime number, it would have been required that 842 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

As a consequence:

842 is a multiple of 1
842 is a multiple of 2
842 is a multiple of 421

For 842 to be a prime number, it would have been required that 842 has only two divisors, i.e., itself and 1.

However, 842 is a semiprime (also called biprime or 2-almost-prime), because it is the product of a two non-necessarily distinct prime numbers. Indeed, 842 = 2 x 421, where 2 and 421 are both prime numbers.

Is 842 a deficient number?

Yes, 842 is a deficient number, that is to say 842 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 842 without 842 itself (that is 1 + 2 + 421 = 424).

Parity of 842

842 is an even number, because it is evenly divisible by 2: 842 / 2 = 421.

Find out more:

What is an even number?

Is 842 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 842 is about 29.017.

Thus, the square root of 842 is not an integer, and therefore 842 is not a square number.

What is the square number of 842?

The square of a number (here 842) is the result of the product of this number (842) by itself (i.e., 842 × 842); the square of 842 is sometimes called "raising 842 to the power 2", or "842 squared".

The square of 842 is 708 964 because 842 × 842 = 842² = 708 964.

As a consequence, 842 is the square root of 708 964.

Number of digits of 842

842 is a number with 3 digits.

What are the multiples of 842?

The multiples of 842 are all integers evenly divisible by 842, that is all numbers such that the remainder of the division by 842 is zero. There are infinitely many multiples of 842. The smallest multiples of 842 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 842 too, since 0 × 842 = 0
842: indeed, 842 is a multiple of itself, since 842 is evenly divisible by 842 (we have 842 / 842 = 1, so the remainder of this division is indeed zero)
1 684: indeed, 1 684 = 842 × 2
2 526: indeed, 2 526 = 842 × 3
3 368: indeed, 3 368 = 842 × 4
4 210: indeed, 4 210 = 842 × 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 842). 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 29.017). 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 842

Preceding numbers: …840, 841
Following numbers: 843, 844…

Nearest numbers from 842

Preceding prime number: 839
Following prime number: 853