28399904 has 48 divisors (see below), whose sum is σ = 60678072. Its totient is φ = 13006848.

The previous prime is 28399901. The next prime is 28399907. The reversal of 28399904 is 40999382.

It is an interprime number because it is at equal distance from previous prime (28399901) and next prime (28399907).

It can be written as a sum of positive squares in 4 ways, for example, as 22543504 + 5856400 = 4748^2 + 2420^2 .

It is not an unprimeable number, because it can be changed into a prime (28399901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96782 + ... + 97074.

Almost surely, 2^28399904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28399904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30339036).

28399904 is an abundant number, since it is smaller than the sum of its proper divisors (32278168).

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

28399904 is a wasteful number, since it uses less digits than its factorization.

28399904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 44.

The square root of 28399904 is about 5329.1560307426. The cubic root of 28399904 is about 305.0977166072.

The spelling of 28399904 in words is "twenty-eight million, three hundred ninety-nine thousand, nine hundred four".