105

105 is a natural number that follows 104 and precedes 106. In mathematics, it is an odd composite number with prime factorization 3 × 5 × 7. It is the product of three consecutive primes, making it a sphenic number. It is also the 14th triangular number, since 14 × 15 / 2 equals 105. Its positive divisors are 1, 3, 5, 7, 15, 21, 35, and 105, for a total of eight.

In numeral systems, 105 appears in several representations. In binary it is 1101001; in decimal it remains 105; in octal it is 151; in hexadecimal it is 0x69. In Roman numerals it is written as CV. The ASCII and Unicode code point 105 corresponds to the lowercase letter 'i'.

In chemistry, 105 is the atomic number of the synthetic element dubnium (Db). Dubnium is a transuranic, highly radioactive element with no stable isotopes. It was first synthesized in 1968 by teams at Dubna and at Lawrence Berkeley National Laboratory, and was named after the Russian city of Dubna. Because it is a heavy, short-lived transactinide, many of its physical and chemical properties are inferred rather than extensively measured, and research continues to refine its characterization.