12345 has 8 divisors (see below), whose sum is σ = 19776. Its totient is φ = 6576.

The previous prime is 12343. The next prime is 12347. The reversal of 12345 is 54321.

12345 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (12343) and next prime (12347).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 12345 - 2¹ = 12343 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15), and also a Moran number because the ratio is a prime number: 823 = 12345 / (1 + 2 + 3 + 4 + 5).

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.

It is not an unprimeable number, because it can be changed into a prime (12343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 397 + ... + 426.

It is an arithmetic number, because the mean of its divisors is an integer number (2472).

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 a deficient number, since it is larger than the sum of its proper divisors (7431).

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 product of its digits is 120, while the sum is 15.

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).

It can be divided in two parts, 1 and 2345, that added together give a triangular number (2346 = T₆₈).

The spelling of 12345 in words is "twelve thousand, three hundred forty-five".