# 1561

## 1,561 is an odd composite number composed of two prime numbers multiplied together.

What does the number 1561 look like?

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

1561 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 1561:

### 7 × 223

See below for interesting mathematical facts about the number 1561 from the Numbermatics database.

### Names of 1561

• Cardinal: 1561 can be written as One thousand, five hundred sixty-one.

### Scientific notation

• Scientific notation: 1.561 × 103

### Factors of 1561

• Number of distinct prime factors ω(n): 2
• Total number of prime factors Ω(n): 2
• Sum of prime factors: 230

### Divisors of 1561

• Number of divisors d(n): 4
• Complete list of divisors:
• Sum of all divisors σ(n): 1792
• Sum of proper divisors (its aliquot sum) s(n): 231
• 1561 is a deficient number, because the sum of its proper divisors (231) is less than itself. Its deficiency is 1330

### Bases of 1561

• Binary: 110000110012
• Base-36: 17D

### Squares and roots of 1561

• 1561 squared (15612) is 2436721
• 1561 cubed (15613) is 3803721481
• The square root of 1561 is 39.5094925303
• The cube root of 1561 is 11.6002576241

### Scales and comparisons

How big is 1561?
• 1,561 seconds is equal to 26 minutes, 1 second.
• To count from 1 to 1,561 would take you about twenty-six 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 1561 cubic inches would be around 1 feet tall.

### Recreational maths with 1561

• 1561 backwards is 1651
• The number of decimal digits it has is: 4
• The sum of 1561's digits is 13
• More coming soon!