138523840 has 224 divisors, whose sum is σ = 417844224. Its totient is φ = 42577920.

The previous prime is 138523829. The next prime is 138523843. The reversal of 138523840 is 48325831.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (224).

It is a junction number, because it is equal to n+sod(n) for n = 138523796 and 138523805.

It is not an unprimeable number, because it can be changed into a prime (138523843) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1951005 + ... + 1951075.

It is an arithmetic number, because the mean of its divisors is an integer number (1865376).

Almost surely, 2^138523840 is an apocalyptic number.

138523840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138523840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (208922112).

138523840 is an abundant number, since it is smaller than the sum of its proper divisors (279320384).

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

138523840 is a wasteful number, since it uses less digits than its factorization.

138523840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 138523840 is about 11769.6151169017. The cubic root of 138523840 is about 517.4179695256.

The spelling of 138523840 in words is "one hundred thirty-eight million, five hundred twenty-three thousand, eight hundred forty".