66889728 has 144 divisors (see below), whose sum is σ = 204422400. Its totient is φ = 21012480.

The previous prime is 66889699. The next prime is 66889729. The reversal of 66889728 is 82798866.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-3 number, since 3×66889728³ (a number of 24 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (66889729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 350113 + ... + 350303.

It is an arithmetic number, because the mean of its divisors is an integer number (1419600).

Almost surely, 2^66889728 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 66889728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102211200).

66889728 is an abundant number, since it is smaller than the sum of its proper divisors (137532672).

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

66889728 is a wasteful number, since it uses less digits than its factorization.

66889728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238 (or 215 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 54.

The square root of 66889728 is about 8178.6140635196. The cubic root of 66889728 is about 405.9318642889.

The spelling of 66889728 in words is "sixty-six million, eight hundred eighty-nine thousand, seven hundred twenty-eight".