28089540 has 72 divisors (see below), whose sum is σ = 86021208. Its totient is φ = 7418880.

The previous prime is 28089539. The next prime is 28089547. The reversal of 28089540 is 4598082.

It can be written as a sum of positive squares in 4 ways, for example, as 20736 + 28068804 = 144^2 + 5298^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 28089495 and 28089504.

It is not an unprimeable number, because it can be changed into a prime (28089547) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19650 + ... + 21030.

It is an arithmetic number, because the mean of its divisors is an integer number (1194739).

Almost surely, 2^28089540 is an apocalyptic number.

28089540 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 28089540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43010604).

28089540 is an abundant number, since it is smaller than the sum of its proper divisors (57931668).

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

28089540 is a wasteful number, since it uses less digits than its factorization.

28089540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1509 (or 1504 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 28089540 is about 5299.9566035959. The cubic root of 28089540 is about 303.9822386899.

The spelling of 28089540 in words is "twenty-eight million, eighty-nine thousand, five hundred forty".