123815 has 4 divisors (see below), whose sum is σ = 148584. Its totient is φ = 99048.

The previous prime is 123803. The next prime is 123817. The reversal of 123815 is 518321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 518321 = 587 ⋅883.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123815 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 123815.

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

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12377 + ... + 12386.

It is an arithmetic number, because the mean of its divisors is an integer number (37146).

2¹²³⁸¹⁵ is an apocalyptic number.

123815 is a deficient number, since it is larger than the sum of its proper divisors (24769).

123815 is an equidigital number, since it uses as much as digits as its factorization.

123815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24768.

The product of its digits is 240, while the sum is 20.

The square root of 123815 is about 351.8735568354. The cubic root of 123815 is about 49.8414980737.

The spelling of 123815 in words is "one hundred twenty-three thousand, eight hundred fifteen".