66385728 has 84 divisors (see below), whose sum is σ = 198595488. Its totient is φ = 21162240.

The previous prime is 66385721. The next prime is 66385763. The reversal of 66385728 is 82758366.

66385728 is a `hidden beast` number, since 6 + 638 + 5 + 7 + 2 + 8 = 666.

It is a super-3 number, since 3×66385728³ (a number of 24 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66385721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10743 + ... + 15753.

It is an arithmetic number, because the mean of its divisors is an integer number (2364232).

Almost surely, 2^66385728 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 66385728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99297744).

66385728 is an abundant number, since it is smaller than the sum of its proper divisors (132209760).

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

66385728 is a wasteful number, since it uses less digits than its factorization.

66385728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5052 (or 5039 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The square root of 66385728 is about 8147.7437367654. The cubic root of 66385728 is about 404.9097558416.

The spelling of 66385728 in words is "sixty-six million, three hundred eighty-five thousand, seven hundred twenty-eight".