# 7991

## 7,991 is an odd composite number composed of two prime numbers multiplied together.

What does the number 7991 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 4 divisors.

7991 is an odd composite number. It is composed of two distinct prime numbers multiplied together. It has a total of four divisors.

## Prime factorization of 7991:

### 61 × 131

See below for interesting mathematical facts about the number 7991 from the Numbermatics database.

### Names of 7991

• Cardinal: 7991 can be written as Seven thousand, nine hundred ninety-one.

### Scientific notation

• Scientific notation: 7.991 × 103

### Factors of 7991

• Number of distinct prime factors ω(n): 2
• Total number of prime factors Ω(n): 2
• Sum of prime factors: 192

### Divisors of 7991

• Number of divisors d(n): 4
• Complete list of divisors:
• Sum of all divisors σ(n): 8184
• Sum of proper divisors (its aliquot sum) s(n): 193
• 7991 is a deficient number, because the sum of its proper divisors (193) is less than itself. Its deficiency is 7798

### Bases of 7991

• Binary: 11111001101112
• Base-36: 65Z

### Squares and roots of 7991

• 7991 squared (79912) is 63856081
• 7991 cubed (79913) is 510273943271
• The square root of 7991 is 89.3923934125
• The cube root of 7991 is 19.9924971859

### Scales and comparisons

How big is 7991?
• 7,991 seconds is equal to 2 hours, 13 minutes, 11 seconds.
• To count from 1 to 7,991 would take you about two hours.

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 7991 cubic inches would be around 1.7 feet tall.

### Recreational maths with 7991

• 7991 backwards is 1997
• The number of decimal digits it has is: 4
• The sum of 7991's digits is 26
• More coming soon!