71 (number) facts for kids

Seventy-one is a number that comes right after seventy and before seventy-two. It is an odd number, which means you can't divide it evenly by two. Seventy-one is also a special kind of number called a prime number.

What is a Prime Number?

A prime number is a whole number greater than 1 that has only two factors (divisors): 1 and itself. This means you can only divide a prime number by 1 and by the number itself to get a whole number answer. For example, 71 can only be divided evenly by 1 and 71.

Other examples of prime numbers include 2, 3, 5, 7, 11, and so on. Numbers that are not prime are called composite numbers. Composite numbers can be divided by more than just 1 and themselves. For instance, 4 is a composite number because it can be divided by 1, 2, and 4.

Interesting Facts About 71

Mathematical Properties

• Odd Number: As mentioned, 71 is an odd number because it doesn't end in 0, 2, 4, 6, or 8.
• Prime Number: It's a prime number, which makes it a building block for other numbers.
• Chen Prime: Seventy-one is a Chen prime. This means that 71 plus 2 (which is 73) is also a prime number.
• Centered Heptagonal Number: 71 is a centered heptagonal number. This is a type of figurate number that represents a heptagon (a seven-sided shape) with a point in the center and other points around it in layers.
• Sum of Primes: 71 can be written as the sum of three consecutive prime numbers: 19 + 23 + 29 = 71.

In Science and Technology

• Atomic Number: In chemistry, 71 is the atomic number of Lutetium, which is a rare earth element.
• Space Exploration: The Soyuz 7K-OKS spacecraft, which was part of the Soviet space program, had a total mass of 7,100 kilograms.

In Culture and Sports

• Year 71: The year 71 AD was a significant year in ancient history.
• Sports Scores: In many sports, like basketball, a score of 71 points might be achieved by a team or player.