28121604 has 96 divisors (see below), whose sum is σ = 81285120. Its totient is φ = 7383552.

The previous prime is 28121603. The next prime is 28121629. The reversal of 28121604 is 40612182.

It is a super-2 number, since 2×28121604² = 1581649223065632, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28121603) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 66907 + ... + 67325.

It is an arithmetic number, because the mean of its divisors is an integer number (846720).

Almost surely, 2^28121604 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 28121604, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40642560).

28121604 is an abundant number, since it is smaller than the sum of its proper divisors (53163516).

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

28121604 is a wasteful number, since it uses less digits than its factorization.

28121604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497 (or 495 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 28121604 is about 5302.9806712829. The cubic root of 28121604 is about 304.0978591924.

Adding to 28121604 its reverse (40612182), we get a palindrome (68733786).

The spelling of 28121604 in words is "twenty-eight million, one hundred twenty-one thousand, six hundred four".