The number 28
Numeral systems
Binary: 11100
Septimal (base 7): 40
Octal: 34
Hexadecimal: 1c
Base 24: 14
Factorization
28 = 2 × 2 × 7
28 has 6 divisors: 1, 2, 4, 7, 14, 28
Sum of all divisors other than 28:
28
Sums & differences
28 is the sum of the first 5 prime numbers: 28 = 2 + 3 + 5 + 7 + 11
Difference of 2 squares: 28 = 82 - 62
Goldbach conjecture: 28 = 23 + 5 = 17 + 11
Characteristics
28 is a perfect number
(a number is perfect if it’s equal to the sum of its divisors other than itself)
28 is a triangular number
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The next triangular is:
3628 is a hexagonal number
Related primes
The 28th prime number is:
107Previous prime number:
23 — Next prime number:
29
