Is 1561 a prime number?

1 561 is an odd number, because it is not evenly divisible by 2.

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• What is an even 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 1 561 is about 39.509.

Thus, the square root of 1 561 is not an integer, and therefore 1 561 is not a square number.

The square of a number (here 1 561) is the result of the product of this number (1 561) by itself (i.e., 1 561 × 1 561); the square of 1 561 is sometimes called "raising 1 561 to the power 2", or "1 561 squared".

The square of 1 561 is 2 436 721 because 1 561 × 1 561 = 1 561² = 2 436 721.

As a consequence, 1 561 is the square root of 2 436 721.

1 561 is a number with 4 digits.

The multiples of 1 561 are all integers evenly divisible by 1 561, that is all numbers such that the remainder of the division by 1 561 is zero. There are infinitely many multiples of 1 561. The smallest multiples of 1 561 are:

• 0: indeed, 0 is divisible by any natural number, and it is thus a multiple of 1 561 too, since 0 × 1 561 = 0
• 1 561: indeed, 1 561 is a multiple of itself, since 1 561 is evenly divisible by 1 561 (we have 1 561 / 1 561 = 1, so the remainder of this division is indeed zero)
• 3 122: indeed, 3 122 = 1 561 × 2
• 4 683: indeed, 4 683 = 1 561 × 3
• 6 244: indeed, 6 244 = 1 561 × 4
• 7 805: indeed, 7 805 = 1 561 × 5
• etc.

• Preceding numbers: …1 559, 1 560
• Following numbers: 1 562, 1 563…

Nearest numbers from 1 561

• Preceding prime number: 1 559
• Following prime number: 1 567

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• 1 561 est-il un nombre premier ?