Adding to 12345678 its reverse (87654321), we get a palindrome (99999999).
12345678 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.
12345678 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
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 a congruent number.
It is an unprimeable number.
Almost surely, 212345678 is an apocalyptic number.
12345678 is a gapful number since it is divisible by the number (18) formed by its first and last digit.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
12345678 is a wasteful number, since it uses less digits than its factorization.
12345678 is an evil number, because the sum of its binary digits is even.
The square root of 12345678 is about 3513.6417005722. The cubic root of 12345678 is about 231.1204184663.
The spelling of 12345678 in words is "twelve million, three hundred forty-five thousand, six hundred seventy-eight".