28209312 has 72 divisors (see below), whose sum is σ = 82211220. Its totient is φ = 9169920.

The previous prime is 28209301. The next prime is 28209329. The reversal of 28209312 is 21390282.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 23386896 + 4822416 = 4836^2 + 2196^2 .

It is a tau number, because it is divible by the number of its divisors (72).

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 11 ways as a sum of consecutive naturals, for example, 10614 + ... + 13002.

Almost surely, 2^28209312 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 28209312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41105610).

28209312 is an abundant number, since it is smaller than the sum of its proper divisors (54001908).

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

28209312 is a wasteful number, since it uses less digits than its factorization.

28209312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2446 (or 2435 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 28209312 is about 5311.2439220958. The cubic root of 28209312 is about 304.4136796581.

Adding to 28209312 its reverse (21390282), we get a palindrome (49599594).

The spelling of 28209312 in words is "twenty-eight million, two hundred nine thousand, three hundred twelve".