28304640 has 432 divisors, whose sum is σ = 124994688. Its totient is φ = 5971968.

The previous prime is 28304569. The next prime is 28304641. The reversal of 28304640 is 4640382.

It is a tau number, because it is divible by the number of its divisors (432).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28304641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2177274 + ... + 2177286.

Almost surely, 2^28304640 is an apocalyptic number.

28304640 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 28304640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (62497344).

28304640 is an abundant number, since it is smaller than the sum of its proper divisors (96690048).

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

28304640 is an equidigital number, since it uses as much as digits as its factorization.

28304640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56 (or 30 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 28304640 is about 5320.2105221504. The cubic root of 28304640 is about 304.7561968177.

The spelling of 28304640 in words is "twenty-eight million, three hundred four thousand, six hundred forty".