138400128 has 192 divisors, whose sum is σ = 435352320. Its totient is φ = 42024960.

The previous prime is 138400127. The next prime is 138400139. The reversal of 138400128 is 821004831.

138400128 is a `hidden beast` number, since 138 + 400 + 128 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138400121) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 724513 + ... + 724703.

It is an arithmetic number, because the mean of its divisors is an integer number (2267460).

Almost surely, 2^138400128 is an apocalyptic number.

138400128 is a gapful number since it is divisible by the number (18) 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 138400128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (217676160).

138400128 is an abundant number, since it is smaller than the sum of its proper divisors (296952192).

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

138400128 is a wasteful number, since it uses less digits than its factorization.

138400128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265 (or 250 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 138400128 is about 11764.3583760441. The cubic root of 138400128 is about 517.2638928536.

Adding to 138400128 its reverse (821004831), we get a palindrome (959404959).

The spelling of 138400128 in words is "one hundred thirty-eight million, four hundred thousand, one hundred twenty-eight".