138565728 has 180 divisors, whose sum is σ = 474486012. Its totient is φ = 39553920.

The previous prime is 138565723. The next prime is 138565769. The reversal of 138565728 is 827565831.

138565728 is a `hidden beast` number, since 13 + 8 + 565 + 72 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138565723) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 126463 + ... + 127553.

Almost surely, 2^138565728 is an apocalyptic number.

138565728 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 138565728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (237243006).

138565728 is an abundant number, since it is smaller than the sum of its proper divisors (335920284).

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

138565728 is a wasteful number, since it uses less digits than its factorization.

138565728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127 (or 1103 counting only the distinct ones).

The product of its digits is 403200, while the sum is 45.

The square root of 138565728 is about 11771.3944798397. The cubic root of 138565728 is about 517.4701179973.

The spelling of 138565728 in words is "one hundred thirty-eight million, five hundred sixty-five thousand, seven hundred twenty-eight".