# 640

## 640 is an even composite number composed of two prime numbers multiplied together.

What does the number 640 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 16 divisors.

640 is an even composite number. It is composed of two distinct prime numbers multiplied together. It has a total of sixteen divisors.

## Prime factorization of 640:

### 27 × 5

(2 × 2 × 2 × 2 × 2 × 2 × 2 × 5)

See below for interesting mathematical facts about the number 640 from the Numbermatics database.

### Names of 640

• Cardinal: 640 can be written as Six hundred forty.

### Scientific notation

• Scientific notation: 6.4 × 102

### Factors of 640

• Number of distinct prime factors ω(n): 2
• Total number of prime factors Ω(n): 8
• Sum of prime factors: 7

### Divisors of 640

• Number of divisors d(n): 16
• Complete list of divisors:
• Sum of all divisors σ(n): 1530
• Sum of proper divisors (its aliquot sum) s(n): 890
• 640 is an abundant number, because the sum of its proper divisors (890) is greater than itself. Its abundance is 250

### Bases of 640

• Binary: 10100000002
• Base-36: HS

### Squares and roots of 640

• 640 squared (6402) is 409600
• 640 cubed (6403) is 262144000
• The square root of 640 is 25.2982212813
• The cube root of 640 is 8.6177387601

### Scales and comparisons

How big is 640?
• 640 seconds is equal to 10 minutes, 40 seconds.
• To count from 1 to 640 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 640 cubic inches would be around 0.7 feet tall.

### Recreational maths with 640

• 640 backwards is 046
• 640 is a Harshad number.
• The number of decimal digits it has is: 3
• The sum of 640's digits is 10
• More coming soon!