# 251

## 251 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 251 look like?

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

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

## Prime factorization of 251:

### 251

See below for interesting mathematical facts about the number 251 from the Numbermatics database.

### Names of 251

• Cardinal: 251 can be written as Two hundred fifty-one.

### Scientific notation

• Scientific notation: 2.51 × 102

### Factors of 251

• Number of distinct prime factors ω(n): 1
• Total number of prime factors Ω(n): 1
• Sum of prime factors: 251

### Divisors of 251

• Number of divisors d(n): 2
• Complete list of divisors:
• Sum of all divisors σ(n): 252
• Sum of proper divisors (its aliquot sum) s(n): 1
• 251 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 250

### Bases of 251

• Binary: 111110112
• Base-36: 6Z

### Squares and roots of 251

• 251 squared (2512) is 63001
• 251 cubed (2513) is 15813251
• The square root of 251 is 15.8429795177
• The cube root of 251 is 6.3079935487

### Scales and comparisons

How big is 251?
• 251 seconds is equal to 4 minutes, 11 seconds.
• To count from 1 to 251 would take you about two 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 251 cubic inches would be around 0.5 feet tall.

### Recreational maths with 251

• 251 backwards is 152
• The number of decimal digits it has is: 3
• The sum of 251's digits is 8
• More coming soon!