28320400 has 60 divisors (see below), whose sum is σ = 68811444. Its totient is φ = 11200000.

The previous prime is 28320373. The next prime is 28320403. The reversal of 28320400 is 402382.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3400336 + 24920064 = 1844^2 + 4992^2 .

It is not an unprimeable number, because it can be changed into a prime (28320403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40050 + ... + 40750.

Almost surely, 2^28320400 is an apocalyptic number.

28320400 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 28320400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34405722).

28320400 is an abundant number, since it is smaller than the sum of its proper divisors (40491044).

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

28320400 is a wasteful number, since it uses less digits than its factorization.

28320400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820 (or 809 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 28320400 is about 5321.6914604287. The cubic root of 28320400 is about 304.8127489885.

Adding to 28320400 its reverse (402382), we get a palindrome (28722782).

The spelling of 28320400 in words is "twenty-eight million, three hundred twenty thousand, four hundred".