28815680 has 56 divisors (see below), whose sum is σ = 72667368. Its totient is φ = 10846208.

The previous prime is 28815667. The next prime is 28815713. The reversal of 28815680 is 8651882.

28815680 = 201² + 202² + ... + 455².

It can be written as a sum of positive squares in 4 ways, for example, as 10291264 + 18524416 = 3208^2 + 4304^2 .

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

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, 2792 + ... + 8088.

Almost surely, 2^28815680 is an apocalyptic number.

28815680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28815680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36333684).

28815680 is an abundant number, since it is smaller than the sum of its proper divisors (43851688).

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

28815680 is a wasteful number, since it uses less digits than its factorization.

28815680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5331 (or 5321 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 38.

The square root of 28815680 is about 5368.0238449545. The cubic root of 28815680 is about 306.5793912534.

The spelling of 28815680 in words is "twenty-eight million, eight hundred fifteen thousand, six hundred eighty".