28390400 has 66 divisors (see below), whose sum is σ = 70437270. Its totient is φ = 11345920.

The previous prime is 28390361. The next prime is 28390403. The reversal of 28390400 is 409382.

It can be written as a sum of positive squares in 3 ways, for example, as 173056 + 28217344 = 416^2 + 5312^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 28390400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28390403) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25046 + ... + 26154.

Almost surely, 2^28390400 is an apocalyptic number.

28390400 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 28390400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35218635).

28390400 is an abundant number, since it is smaller than the sum of its proper divisors (42046870).

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

28390400 is a wasteful number, since it uses less digits than its factorization.

28390400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1139 (or 1116 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 28390400 is about 5328.2642577109. The cubic root of 28390400 is about 305.0636792596.

Adding to 28390400 its reverse (409382), we get a palindrome (28799782).

The spelling of 28390400 in words is "twenty-eight million, three hundred ninety thousand, four hundred".