16,777,215
16,777,215 is 2²⁴ − 1, the largest twenty-four-bit value and the number of colours in a true-colour image less one.
- Odd
- Composite
Why 16,777,215 is special
Written in hexadecimal it is FFFFFF, which is why white is written that way in CSS and in every colour picker. The count of distinct colours is one more — 16,777,216 — and the off-by-one between the largest value and the number of values is the most common source of confusion about it.
Factors & digit properties
- Divisors (96)
- 1, 3, 5, 7, 9, 13, 15, 17, 21, 35, 39, 45, 51, 63, 65, 85, 91, 105, 117, 119, 153, 195, 221, 241, 255, 273, 315, 357, 455, 585, 595, 663, 723, 765, 819, 1071, 1105, 1205, 1365, 1547, 1687, 1785, 1989, 2169, 3133, 3315, 3615, 4095, 4097, 4641, 5061, 5355, 7735, 8435, 9399, 9945, 10845, 12291, 13923, 15183, 15665, 20485, 21931, 23205, 25305, 28197, 28679, 36873, 46995, 53261, 61455, 65793, 69615, 75915, 86037, 109655, 140985, 143395, 159783, 184365, 197379, 258111, 266305, 328965, 372827, 430185, 479349, 798915, 986895, 1118481, 1290555, 1864135, 2396745, 3355443, 5592405, 16777215
- Prime factorisation
- 3^2 × 5 × 7 × 13 × 17 × 241
- Digit sum
- 36
- Digital root
- 9
Representations
- Decimal
- 16777215
- Scientific notation
- 1.678 × 10^7
Roman numerals
Roman numerals as modelled here goes up to 3,999.
Binary
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 × 8,388,608 + 1 × 4,194,304 + 1 × 2,097,152 + 1 × 1,048,576 + 1 × 524,288 + 1 × 262,144 + 1 × 131,072 + 1 × 65,536 + 1 × 32,768 + 1 × 16,384 + 1 × 8,192 + 1 × 4,096 + 1 × 2,048 + 1 × 1,024 + 1 × 512 + 1 × 256 + 1 × 128 + 1 × 64 + 1 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 1 × 2 + 1 × 1 = 16,777,215
Octal
7 7 7 7 7 7 7 7
7 × 2,097,152 + 7 × 262,144 + 7 × 32,768 + 7 × 4,096 + 7 × 512 + 7 × 64 + 7 × 8 + 7 × 1 = 16,777,215
Hexadecimal
f f f f f f
f × 1,048,576 + f × 65,536 + f × 4,096 + f × 256 + f × 16 + f × 1 = 16,777,215
Other mathematical patterns
- Abundant number
Technology & computing
The largest value that fits in twenty-four bits is 16,777,215. Written FFFFFF in hexadecimal, which is why that is how white is spelled in CSS. The number of distinct colours is one higher, and the gap between the largest value and the count is the most common confusion about it.
DocumentedTechnology & computingGeography: worldwide
Common questions
Is 16,777,215 a prime number?
No, 16,777,215 is not prime.
What are the factors of 16,777,215?
The factors of 16,777,215 are 1, 3, 5, 7, 9, 13, 15, 17, 21, 35, 39, 45, 51, 63, 65, 85, 91, 105, 117, 119, 153, 195, 221, 241, 255, 273, 315, 357, 455, 585, 595, 663, 723, 765, 819, 1071, 1105, 1205, 1365, 1547, 1687, 1785, 1989, 2169, 3133, 3315, 3615, 4095, 4097, 4641, 5061, 5355, 7735, 8435, 9399, 9945, 10845, 12291, 13923, 15183, 15665, 20485, 21931, 23205, 25305, 28197, 28679, 36873, 46995, 53261, 61455, 65793, 69615, 75915, 86037, 109655, 140985, 143395, 159783, 184365, 197379, 258111, 266305, 328965, 372827, 430185, 479349, 798915, 986895, 1118481, 1290555, 1864135, 2396745, 3355443, 5592405, 16777215.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026