28784557 has 8 divisors (see below), whose sum is σ = 29970296. Its totient is φ = 27620352.

The previous prime is 28784549. The next prime is 28784579. The reversal of 28784557 is 75548782.

It can be written as a sum of positive squares in 4 ways, for example, as 3924361 + 24860196 = 1981^2 + 4986^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28784557 - 2³ = 28784549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28784527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2628 + ... + 8029.

It is an arithmetic number, because the mean of its divisors is an integer number (3746287).

Almost surely, 2^28784557 is an apocalyptic number.

It is an amenable number.

28784557 is a deficient number, since it is larger than the sum of its proper divisors (1185739).

28784557 is a wasteful number, since it uses less digits than its factorization.

28784557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10767.

The product of its digits is 627200, while the sum is 46.

The square root of 28784557 is about 5365.1241364949. The cubic root of 28784557 is about 306.4689755852.

The spelling of 28784557 in words is "twenty-eight million, seven hundred eighty-four thousand, five hundred fifty-seven".