12345 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a d-powerful number, because it can be written as 1 + 213 + 3 + 45 + 55 .
It is an alternating number because its digits alternate between odd and even.
It is a Curzon number.
It is a straight-line number, since its digits are in arithmetic progression.
It is a plaindrome in base 10.
212345 is an apocalyptic number.
12345 is a gapful number since it is divisible by the number (15) formed by its first and last digit.
It is an amenable number.
12345 is an equidigital number, since it uses as much as digits as its factorization.
12345 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 831.
The square root of 12345 is about 111.1080555135. The cubic root of 12345 is about 23.1116187498. Note that the first 3 decimals are identical.
Adding to 12345 its reverse (54321), we get a palindrome (66666).
The spelling of 12345 in words is "twelve thousand, three hundred forty-five".