28320640 has 128 divisors (see below), whose sum is σ = 76010400. Its totient is φ = 10027008.

The previous prime is 28320637. The next prime is 28320641. The reversal of 28320640 is 4602382.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28320641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 206652 + ... + 206788.

Almost surely, 2^28320640 is an apocalyptic number.

28320640 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 28320640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38005200).

28320640 is an abundant number, since it is smaller than the sum of its proper divisors (47689760).

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

28320640 is a wasteful number, since it uses less digits than its factorization.

28320640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192 (or 180 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 28320640 is about 5321.7140096025. The cubic root of 28320640 is about 304.8136100269.

The spelling of 28320640 in words is "twenty-eight million, three hundred twenty thousand, six hundred forty".