Is 385 a prime number?

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

For 385, the answer is: No, 385 is not a prime number.

The list of all positive divisors (i.e., the list of all integers that divide 385) is as follows: 1, 5, 7, 11, 35, 55, 77, 385.

For 385 to be a prime number, it would have been required that 385 has only two divisors, i.e., itself and 1.

Find out more:

What is a prime number?

Actually, one can immediately see that 385 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 385 is 5, so it is divisible by 5 and is therefore not prime.

As a consequence:

385 is a multiple of 1
385 is a multiple of 5
385 is a multiple of 7
385 is a multiple of 11
385 is a multiple of 35
385 is a multiple of 55
385 is a multiple of 77

For 385 to be a prime number, it would have been required that 385 has only two divisors, i.e., itself and 1.

Is 385 a deficient number?

Yes, 385 is a deficient number, that is to say 385 is a natural number that is strictly larger than the sum of its proper divisors, i.e., the divisors of 385 without 385 itself (that is 1 + 5 + 7 + 11 + 35 + 55 + 77 = 191).

Parity of 385

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

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What is an even number?

Is 385 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 385 is about 19.621.

Thus, the square root of 385 is not an integer, and therefore 385 is not a square number.

What is the square number of 385?

The square of a number (here 385) is the result of the product of this number (385) by itself (i.e., 385 × 385); the square of 385 is sometimes called "raising 385 to the power 2", or "385 squared".

The square of 385 is 148 225 because 385 × 385 = 385² = 148 225.

As a consequence, 385 is the square root of 148 225.

Number of digits of 385

385 is a number with 3 digits.

What are the multiples of 385?

The multiples of 385 are all integers evenly divisible by 385, that is all numbers such that the remainder of the division by 385 is zero. There are infinitely many multiples of 385. The smallest multiples of 385 are:

0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 385 too, since 0 × 385 = 0
385: indeed, 385 is a multiple of itself, since 385 is evenly divisible by 385 (we have 385 / 385 = 1, so the remainder of this division is indeed zero)
770: indeed, 770 = 385 × 2
1 155: indeed, 1 155 = 385 × 3
1 540: indeed, 1 540 = 385 × 4
1 925: indeed, 1 925 = 385 × 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 385). 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 19.621). 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 385

Preceding numbers: …383, 384
Following numbers: 386, 387…

Nearest numbers from 385

Preceding prime number: 383
Following prime number: 389