28538640 has 120 divisors (see below), whose sum is σ = 103248600. Its totient is φ = 7022592.

The previous prime is 28538633. The next prime is 28538659. The reversal of 28538640 is 4683582.

28538640 is a `hidden beast` number, since 2 + 8 + 5 + 3 + 8 + 640 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 278784 + 28259856 = 528^2 + 5316^2 .

It is a tau number, because it is divible by the number of its divisors (120).

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 = 28538595 and 28538604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7836 + ... + 10884.

It is an arithmetic number, because the mean of its divisors is an integer number (860405).

Almost surely, 2^28538640 is an apocalyptic number.

28538640 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 28538640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51624300).

28538640 is an abundant number, since it is smaller than the sum of its proper divisors (74709960).

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

28538640 is a wasteful number, since it uses less digits than its factorization.

28538640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3081 (or 3072 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 28538640 is about 5342.1568677829. The cubic root of 28538640 is about 305.5937194327.

The spelling of 28538640 in words is "twenty-eight million, five hundred thirty-eight thousand, six hundred forty".