12345666678 has 20 divisors (see below), whose sum is σ = 27663438660. Its totient is φ = 4115222172.

The previous prime is 12345666677. The next prime is 12345666721. The reversal of 12345666678 is 87666654321.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12345666677) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 38103748 + ... + 38104071.

It is an arithmetic number, because the mean of its divisors is an integer number (1383171933).

Almost surely, 2^12345666678 is an apocalyptic number.

12345666678 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

12345666678 is an abundant number, since it is smaller than the sum of its proper divisors (15317771982).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

12345666678 is an equidigital number, since it uses as much as digits as its factorization.

12345666678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76207833 (or 76207824 counting only the distinct ones).

The product of its digits is 8709120, while the sum is 54.

The spelling of 12345666678 in words is "twelve billion, three hundred forty-five million, six hundred sixty-six thousand, six hundred seventy-eight".