28400400 has 360 divisors, whose sum is σ = 119932800. Its totient is φ = 6209280.

The previous prime is 28400357. The next prime is 28400419. The reversal of 28400400 is 400482.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

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 71 ways as a sum of consecutive naturals, for example, 1234789 + ... + 1234811.

Almost surely, 2^28400400 is an apocalyptic number.

28400400 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 28400400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59966400).

28400400 is an abundant number, since it is smaller than the sum of its proper divisors (91532400).

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

28400400 is a wasteful number, since it uses less digits than its factorization.

28400400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 28400400 is about 5329.2025669888. The cubic root of 28400400 is about 305.0994927586.

Adding to 28400400 its reverse (400482), we get a palindrome (28800882).

The spelling of 28400400 in words is "twenty-eight million, four hundred thousand, four hundred".