# 405

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

What does the number 405 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 10 divisors.

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

## Prime factorization of 405:

### 34 × 5

(3 × 3 × 3 × 3 × 5)

See below for interesting mathematical facts about the number 405 from the Numbermatics database.

### Names of 405

• Cardinal: 405 can be written as Four hundred five.

### Scientific notation

• Scientific notation: 4.05 × 102

### Factors of 405

• Number of distinct prime factors ω(n): 2
• Total number of prime factors Ω(n): 5
• Sum of prime factors: 8

### Divisors of 405

• Number of divisors d(n): 10
• Complete list of divisors:
• Sum of all divisors σ(n): 726
• Sum of proper divisors (its aliquot sum) s(n): 321
• 405 is a deficient number, because the sum of its proper divisors (321) is less than itself. Its deficiency is 84

### Bases of 405

• Binary: 1100101012
• Base-36: B9

### Squares and roots of 405

• 405 squared (4052) is 164025
• 405 cubed (4053) is 66430125
• The square root of 405 is 20.1246117975
• The cube root of 405 is 7.3986362229

### Scales and comparisons

How big is 405?
• 405 seconds is equal to 6 minutes, 45 seconds.
• To count from 1 to 405 would take you about three 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 405 cubic inches would be around 0.6 feet tall.

### Recreational maths with 405

• 405 backwards is 504
• 405 is a Harshad number.
• The number of decimal digits it has is: 3
• The sum of 405's digits is 9
• More coming soon!