123438021 has 16 divisors (see below), whose sum is σ = 188272128. Its totient is φ = 70470000.

The previous prime is 123438017. The next prime is 123438023. The reversal of 123438021 is 120834321.

It is not a de Polignac number, because 123438021 - 2² = 123438017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 123437982 and 123438000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123438023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28446 + ... + 32496.

It is an arithmetic number, because the mean of its divisors is an integer number (11767008).

Almost surely, 2^123438021 is an apocalyptic number.

It is an amenable number.

123438021 is a deficient number, since it is larger than the sum of its proper divisors (64834107).

123438021 is a wasteful number, since it uses less digits than its factorization.

123438021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5512.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 123438021 is about 11110.2664684516. The cubic root of 123438021 is about 497.9086258380.

The spelling of 123438021 in words is "one hundred twenty-three million, four hundred thirty-eight thousand, twenty-one".