345

345 is a natural number that comes after 344 and before 346. It is an odd composite number with prime factorization 3 × 5 × 23. Its positive divisors are 1, 3, 5, 15, 23, 69, 115, and 345.

In base-10, the digits are 3, 4, and 5, which are consecutive integers. The Roman numeral for 345 is CCCXLV. The number is divisible by 3 and by 5, and hence by 15 as well; equivalently, 345 is congruent to 0 modulo 3 and modulo 5, and to 3 modulo 6.

In mathematics, 345 is not a triangular number nor a square, but it can be expressed as a product of three distinct primes. It is a member of various arithmetic progressions that involve multiples of 3 and 5.

In telephony, 345 is the area code for the Cayman Islands within the North American Numbering Plan, used after the country code +1 for phone numbers in that territory.

The digits 3, 4, and 5 form a well-known sequence associated with the 3-4-5 triangle in geometry, a primitive Pythagorean triple. This connection to a classic right triangle is a common reference in educational contexts and explains why the numbers 3, 4, and 5 often appear together.