# 639

## 639 is an odd composite number composed of two prime numbers multiplied together.

What does the number 639 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 6 divisors.

639 is an odd composite number. It is composed of two distinct prime numbers multiplied together. It has a total of six divisors.

## Prime factorization of 639:

### 32 × 71

(3 × 3 × 71)

See below for interesting mathematical facts about the number 639 from the Numbermatics database.

### Names of 639

• Cardinal: 639 can be written as Six hundred thirty-nine.

### Scientific notation

• Scientific notation: 6.39 × 102

### Factors of 639

• Number of distinct prime factors ω(n): 2
• Total number of prime factors Ω(n): 3
• Sum of prime factors: 74

### Divisors of 639

• Number of divisors d(n): 6
• Complete list of divisors:
• Sum of all divisors σ(n): 936
• Sum of proper divisors (its aliquot sum) s(n): 297
• 639 is a deficient number, because the sum of its proper divisors (297) is less than itself. Its deficiency is 342

### Bases of 639

• Binary: 10011111112
• Base-36: HR

### Squares and roots of 639

• 639 squared (6392) is 408321
• 639 cubed (6393) is 260917119
• The square root of 639 is 25.2784493197
• The cube root of 639 is 8.6132480147

### Scales and comparisons

How big is 639?
• 639 seconds is equal to 10 minutes, 39 seconds.
• To count from 1 to 639 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 639 cubic inches would be around 0.7 feet tall.

### Recreational maths with 639

• 639 backwards is 936
• The number of decimal digits it has is: 3
• The sum of 639's digits is 18
• More coming soon!