28557216 has 72 divisors (see below), whose sum is σ = 81752580. Its totient is φ = 9455616.

The previous prime is 28557173. The next prime is 28557227. The reversal of 28557216 is 61275582.

It is a happy number.

28557216 is a `hidden beast` number, since 2 + 85 + 572 + 1 + 6 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 28515600 + 41616 = 5340^2 + 204^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 65736 + ... + 66168.

Almost surely, 2^28557216 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 28557216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40876290).

28557216 is an abundant number, since it is smaller than the sum of its proper divisors (53195364).

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

28557216 is a wasteful number, since it uses less digits than its factorization.

28557216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678 (or 667 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 28557216 is about 5343.8952085534. The cubic root of 28557216 is about 305.6600094137.

The spelling of 28557216 in words is "twenty-eight million, five hundred fifty-seven thousand, two hundred sixteen".