# 661

## 661 is a prime number. Like all primes greater than two, it is odd and has no factors apart from itself and one.

What does the number 661 look like?

As a prime, it is not composed of any other numbers and has no internal structure.

661 is a prime number. Like all primes (except two), it is an odd number.

## Prime factorization of 661:

### 661

See below for interesting mathematical facts about the number 661 from the Numbermatics database.

### Names of 661

• Cardinal: 661 can be written as Six hundred sixty-one.

### Scientific notation

• Scientific notation: 6.61 × 102

### Factors of 661

• Number of distinct prime factors ω(n): 1
• Total number of prime factors Ω(n): 1
• Sum of prime factors: 661

### Divisors of 661

• Number of divisors d(n): 2
• Complete list of divisors:
• Sum of all divisors σ(n): 662
• Sum of proper divisors (its aliquot sum) s(n): 1
• 661 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 660

### Bases of 661

• Binary: 10100101012
• Base-36: ID

### Squares and roots of 661

• 661 squared (6612) is 436921
• 661 cubed (6613) is 288804781
• The square root of 661 is 25.7099202643
• The cube root of 661 is 8.7109827387

### Scales and comparisons

How big is 661?
• 661 seconds is equal to 11 minutes, 1 second.
• To count from 1 to 661 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 661 cubic inches would be around 0.7 feet tall.

### Recreational maths with 661

• 661 backwards is 166
• The number of decimal digits it has is: 3
• The sum of 661's digits is 13
• More coming soon!