138123840 has 56 divisors (see below), whose sum is σ = 438546240. Its totient is φ = 36832768.

The previous prime is 138123833. The next prime is 138123841. The reversal of 138123840 is 48321831.

138123840 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 138123798 and 138123807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138123841) 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 7 ways as a sum of consecutive naturals, for example, 70980 + ... + 72899.

Almost surely, 2^138123840 is an apocalyptic number.

138123840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

138123840 is an abundant number, since it is smaller than the sum of its proper divisors (300422400).

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

138123840 is a wasteful number, since it uses less digits than its factorization.

138123840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143899 (or 143889 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 138123840 is about 11752.6099229065. The cubic root of 138123840 is about 516.9194591366.

The spelling of 138123840 in words is "one hundred thirty-eight million, one hundred twenty-three thousand, eight hundred forty".