123818 has 4 divisors (see below), whose sum is σ = 185730. Its totient is φ = 61908.

The previous prime is 123817. The next prime is 123821. The reversal of 123818 is 818321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 818321 = 7 ⋅116903.

It can be written as a sum of positive squares in only one way, i.e., 76729 + 47089 = 277^2 + 217^2 .

It is an Ulam number.

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

It is a junction number, because it is equal to n+sod(n) for n = 123793 and 123802.

It is not an unprimeable number, because it can be changed into a prime (123817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30953 + ... + 30956.

2¹²³⁸¹⁸ is an apocalyptic number.

123818 is a deficient number, since it is larger than the sum of its proper divisors (61912).

123818 is an equidigital number, since it uses as much as digits as its factorization.

123818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61911.

The product of its digits is 384, while the sum is 23.

The square root of 123818 is about 351.8778197045. The cubic root of 123818 is about 49.8419006186.

The spelling of 123818 in words is "one hundred twenty-three thousand, eight hundred eighteen".