138428640 has 288 divisors, whose sum is σ = 558544896. Its totient is φ = 30551040.

The previous prime is 138428621. The next prime is 138428683. The reversal of 138428640 is 46824831.

138428640 is a `hidden beast` number, since 1 + 3 + 8 + 4 + 2 + 8 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 138428595 and 138428604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 312259 + ... + 312701.

It is an arithmetic number, because the mean of its divisors is an integer number (1939392).

Almost surely, 2^138428640 is an apocalyptic number.

138428640 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 138428640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (279272448).

138428640 is an abundant number, since it is smaller than the sum of its proper divisors (420116256).

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

138428640 is a wasteful number, since it uses less digits than its factorization.

138428640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502 (or 491 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 138428640 is about 11765.5701094337. The cubic root of 138428640 is about 517.2994111624.

The spelling of 138428640 in words is "one hundred thirty-eight million, four hundred twenty-eight thousand, six hundred forty".