Prime Factorize A Sean

Divisibility Check ▼

Check what numbers divide evenly into your number.

Prime Factorization Tree ▼

Enter a number to see its prime factors displayed as a tree with branches.

Compare Two Numbers (GCF)

Enter two numbers to compare their factorization trees and find their Greatest Common Factor.

Polynomial Factoring ▼

Factor polynomials using standard notation. Use ^ for exponents or paste directly from MathJax.

Examples: x^2 + 5x + 6 | x² + 5x + 6 | 2x^2 - 8 | x^2 - 4

Factor Single Polynomial or Fraction

Compare Two Polynomials (GCF)

Find the Greatest Common Factor of two polynomials.

Find Nth Prime Number ▼

Enter a position to find the prime number at that position (e.g., 182 for the 182nd prime).

Screensaver Controls ▼

Control the animated background showing prime numbers and their multiples.

Start Prime: End Prime:

Speed: 5

Min Multiplier: Max Multiplier:

Random Prime Order (Select prime numbers randomly instead of sequentially)

Number	Divisibility Rule	Example
2	The last digit should be even (0, 2, 4, 6, or 8).	128 (last digit 8)
3	The sum of the digits should be divisible by 3.	123 (1+2+3=6)
4	The number formed by the last two digits should be divisible by 4.	316 (16÷4=4)
5	The last digit should either be 0 or 5.	125 (last digit 5)
6	The number should be divisible by both 2 and 3.	126 (even, 1+2+6=9)
7	The double of the last digit, when subtracted from the rest of the number, the difference obtained should be divisible by 7.	343 (34-6=28)
8	The number formed by the last three digits should be divisible by 8.	1024 (024÷8=3)
9	The sum of the digits should be divisible by 9.	729 (7+2+9=18)
10	The last digit should be 0.	150 (last digit 0)
11	The difference of the alternating sum of digits should be divisible by 11.	121 (1-2+1=0)
12	The number should be divisible by both 3 and 4.	144 (1+4+4=9, 44÷4=11)
13	The four times of the last digit, when added to the rest of the number, the result obtained should be divisible by 13.	169 (16+36=52)
14	Upon adding the last two digits to twice the sum of the remaining digits, the result should be divisible by 14.	154 (54+2=56)
15	The number should be divisible by both 5 and 3.	135 (ends in 5, 1+3+5=9)
16	The last four digits should be divisible by 16.	2048 (2048÷16=128)
17	Five times the last digit, when subtracted from the rest of the number, should be divisible by 17.	221 (22-5=17)
19	Double the last digit, and add it to the rest of the number. If the result is divisible by 19, so is the original number.	209 (20+18=38)