# 645

## 645 is an odd composite number composed of three prime numbers multiplied together.

What does the number 645 look like?

This visualization shows the relationship between its 3 prime factors (large circles) and 8 divisors.

645 is an odd composite number. It is composed of three distinct prime numbers multiplied together. It has a total of eight divisors.

## Prime factorization of 645:

### 3 × 5 × 43

See below for interesting mathematical facts about the number 645 from the Numbermatics database.

### Names of 645

• Cardinal: 645 can be written as Six hundred forty-five.

### Scientific notation

• Scientific notation: 6.45 × 102

### Factors of 645

• Number of distinct prime factors ω(n): 3
• Total number of prime factors Ω(n): 3
• Sum of prime factors: 51

### Divisors of 645

• Number of divisors d(n): 8
• Complete list of divisors:
• Sum of all divisors σ(n): 1056
• Sum of proper divisors (its aliquot sum) s(n): 411
• 645 is a deficient number, because the sum of its proper divisors (411) is less than itself. Its deficiency is 234

### Bases of 645

• Binary: 10100001012
• Base-36: HX

### Squares and roots of 645

• 645 squared (6452) is 416025
• 645 cubed (6453) is 268336125
• The square root of 645 is 25.3968501985
• The cube root of 645 is 8.6401225977

### Scales and comparisons

How big is 645?
• 645 seconds is equal to 10 minutes, 45 seconds.
• To count from 1 to 645 would take you about five minutes.

This is a very rough estimate, based on a speaking rate of half a second every third order of magnitude. If you speak quickly, you could probably say any randomly-chosen number between one and a thousand in around half a second. Very big numbers obviously take longer to say, so we add half a second for every extra x1000. (We do not count involuntary pauses, bathroom breaks or the necessity of sleep in our calculation!)

• A cube with a volume of 645 cubic inches would be around 0.7 feet tall.

### Recreational maths with 645

• 645 backwards is 546
• 645 is a Harshad number.
• The number of decimal digits it has is: 3
• The sum of 645's digits is 15
• More coming soon!

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Chicago style:
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The information we have on file for 645 includes mathematical data and numerical statistics calculated using standard algorithms and methods. We are adding more all the time. If there are any features you would like to see, please contact us. Information provided for educational use, intellectual curiosity and fun!

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