28208640 has 80 divisors (see below), whose sum is σ = 90204048. Its totient is φ = 7520256.

The previous prime is 28208581. The next prime is 28208641. The reversal of 28208640 is 4680282.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 28208598 and 28208607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28208641) 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, 5844 + ... + 9516.

Almost surely, 2^28208640 is an apocalyptic number.

28208640 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 28208640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45102024).

28208640 is an abundant number, since it is smaller than the sum of its proper divisors (61995408).

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

28208640 is an equidigital number, since it uses as much as digits as its factorization.

28208640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3699 (or 3683 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 30.

The square root of 28208640 is about 5311.1806597027. The cubic root of 28208640 is about 304.4112623994.

The spelling of 28208640 in words is "twenty-eight million, two hundred eight thousand, six hundred forty".