75781728 has 144 divisors (see below), whose sum is σ = 247665600. Its totient is φ = 21738240.

The previous prime is 75781723. The next prime is 75781729. The reversal of 75781728 is 82718757.

75781728 is a `hidden beast` number, since 7 + 578 + 1 + 72 + 8 = 666.

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

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (75781721) 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, 59563 + ... + 60821.

It is an arithmetic number, because the mean of its divisors is an integer number (1719900).

Almost surely, 2^75781728 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 75781728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123832800).

75781728 is an abundant number, since it is smaller than the sum of its proper divisors (171883872).

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

75781728 is a wasteful number, since it uses less digits than its factorization.

75781728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1305 (or 1294 counting only the distinct ones).

The product of its digits is 219520, while the sum is 45.

The square root of 75781728 is about 8705.2701279168. The cubic root of 75781728 is about 423.1764600860.

The spelling of 75781728 in words is "seventy-five million, seven hundred eighty-one thousand, seven hundred twenty-eight".