Number reference
38 explained.
38: thirty-eight, composite; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- thirty-eight
- Classification
- composite
- Factors
- 1, 2, 19, 38
- Prime factorization
- 2 × 19
- Square root
- 6.164414
- Cube root
- 3.361975
- Binary
- 100110
- Octal
- 46
- Hexadecimal
- 26
- Roman numeral
- XXXVIII
- Digit sum
- 11
- Digital root
- 2
What makes 38 notable
- Semiprime. 38 = 2 × 19, a product of exactly two primes. That gives it just four divisors, so it splits into equal groups in only two non-trivial ways.
38 in everyday use
The 38th parallel divided Korea after 1945 and remains a shorthand for the border between North and South. Thirty-eight is the atomic number of strontium, whose salts colour fireworks red. An American roulette wheel has 38 pockets — the numbers 1 to 36 plus 0 and 00 — which is what gives the house its edge over the European wheel. The .38 Special was the standard police revolver cartridge in the United States for much of the twentieth century.
Thirty-eight is the sum of the squares of the first three primes, 4 + 9 + 25, and it factors as 2 × 19. It is the largest even number that cannot be written as the sum of two odd composite numbers; 40 is 15 + 25, and every larger even number has such a split. Thirty-eight is also the magic constant of the only possible magic hexagon, in which the numbers 1 to 19 fill a hexagonal grid so every straight line sums to 38.
Nearby numbers
How to read this page
The factor list shows every way 38 splits into equal whole-number groups — 4 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 38 for contexts that do not use decimal.
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