138481728 has 448 divisors, whose sum is σ = 526694400. Its totient is φ = 30965760.

The previous prime is 138481727. The next prime is 138481753. The reversal of 138481728 is 827184831.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 138481728.

It is not an unprimeable number, because it can be changed into a prime (138481727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4775218 + ... + 4775246.

Almost surely, 2^138481728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 138481728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (263347200).

138481728 is an abundant number, since it is smaller than the sum of its proper divisors (388212672).

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

138481728 is a wasteful number, since it uses less digits than its factorization.

138481728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98 (or 88 counting only the distinct ones).

The product of its digits is 86016, while the sum is 42.

The square root of 138481728 is about 11767.8259674419. The cubic root of 138481728 is about 517.3655315867.

It can be divided in two parts, 13848 and 1728, that added together give a triangular number (15576 = T₁₇₆).

The spelling of 138481728 in words is "one hundred thirty-eight million, four hundred eighty-one thousand, seven hundred twenty-eight".