123456 has 28 divisors (see below), whose sum is σ = 327152. Its totient is φ = 41088.

The previous prime is 123449. The next prime is 123457. The reversal of 123456 is 654321.

It is a happy number.

123456 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is an Ulam number.

It is an alternating number because its digits alternate between odd and even.

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 (123457) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130 + ... + 513.

It is an arithmetic number, because the mean of its divisors is an integer number (11684).

2¹²³⁴⁵⁶ is an apocalyptic number.

123456 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

123456 is an abundant number, since it is smaller than the sum of its proper divisors (203696).

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

123456 is an equidigital number, since it uses as much as digits as its factorization.

123456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658 (or 648 counting only the distinct ones).

The product of its digits is 720, while the sum is 21.

The square root of 123456 is about 351.3630600960. The cubic root of 123456 is about 49.7932798467.

Adding to 123456 its reverse (654321), we get a palindrome (777777).

The spelling of 123456 in words is "one hundred twenty-three thousand, four hundred fifty-six".