138439840 has 192 divisors, whose sum is σ = 432407808. Its totient is φ = 40550400.

The previous prime is 138439817. The next prime is 138439859. The reversal of 138439840 is 48934831.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 138439793 and 138439802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 209110 + ... + 209770.

It is an arithmetic number, because the mean of its divisors is an integer number (2252124).

Almost surely, 2^138439840 is an apocalyptic number.

138439840 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 138439840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (216203904).

138439840 is an abundant number, since it is smaller than the sum of its proper divisors (293967968).

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

138439840 is a wasteful number, since it uses less digits than its factorization.

138439840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 711 (or 703 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 40.

The square root of 138439840 is about 11766.0460648427. The cubic root of 138439840 is about 517.3133620259.

The spelling of 138439840 in words is "one hundred thirty-eight million, four hundred thirty-nine thousand, eight hundred forty".