28781856 has 108 divisors (see below), whose sum is σ = 85272642. Its totient is φ = 9206784.

The previous prime is 28781849. The next prime is 28781873. The reversal of 28781856 is 65818782.

It can be written as a sum of positive squares in 3 ways, for example, as 28515600 + 266256 = 5340^2 + 516^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 394236 + ... + 394308.

Almost surely, 2^28781856 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 28781856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42636321).

28781856 is an abundant number, since it is smaller than the sum of its proper divisors (56490786).

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

28781856 is a wasteful number, since it uses less digits than its factorization.

28781856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163 (or 115 counting only the distinct ones).

The product of its digits is 215040, while the sum is 45.

The square root of 28781856 is about 5364.8724122760. The cubic root of 28781856 is about 306.4593894427.

The spelling of 28781856 in words is "twenty-eight million, seven hundred eighty-one thousand, eight hundred fifty-six".