28005520 has 40 divisors (see below), whose sum is σ = 65480184. Its totient is φ = 11139072.

The previous prime is 28005491. The next prime is 28005521. The reversal of 28005520 is 2550082.

It can be written as a sum of positive squares in 4 ways, for example, as 10163344 + 17842176 = 3188^2 + 4224^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 28005491 and 28005500.

It is not an unprimeable number, because it can be changed into a prime (28005521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14872 + ... + 16648.

Almost surely, 2^28005520 is an apocalyptic number.

28005520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28005520 is an abundant number, since it is smaller than the sum of its proper divisors (37474664).

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

28005520 is a wasteful number, since it uses less digits than its factorization.

28005520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1987 (or 1981 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 28005520 is about 5292.0241873975. The cubic root of 28005520 is about 303.6788506039.

The spelling of 28005520 in words is "twenty-eight million, five thousand, five hundred twenty".