28281728 has 64 divisors (see below), whose sum is σ = 61506000. Its totient is φ = 12902400.

The previous prime is 28281691. The next prime is 28281731. The reversal of 28281728 is 82718282.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×28281728² = 1599712277331968, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a junction number, because it is equal to n+sod(n) for n = 28281691 and 28281700.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70328 + ... + 70728.

Almost surely, 2^28281728 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 28281728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30753000).

28281728 is an abundant number, since it is smaller than the sum of its proper divisors (33224272).

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

28281728 is a wasteful number, since it uses less digits than its factorization.

28281728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463 (or 451 counting only the distinct ones).

The product of its digits is 28672, while the sum is 38.

The square root of 28281728 is about 5318.0567879631. The cubic root of 28281728 is about 304.6739434144.

The spelling of 28281728 in words is "twenty-eight million, two hundred eighty-one thousand, seven hundred twenty-eight".