28004 has 6 divisors (see below), whose sum is σ = 49014. Its totient is φ = 14000.

The previous prime is 28001. The next prime is 28019. The reversal of 28004 is 40082.

It can be written as a sum of positive squares in only one way, i.e., 23104 + 4900 = 152^2 + 70^2 .

It is a nialpdrome in base 8 and base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 28004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3497 + ... + 3504.

It is an arithmetic number, because the mean of its divisors is an integer number (8169).

2²⁸⁰⁰⁴ is an apocalyptic number.

It is an amenable number.

28004 is a deficient number, since it is larger than the sum of its proper divisors (21010).

28004 is a wasteful number, since it uses less digits than its factorization.

28004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7005 (or 7003 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 28004 is about 167.3439571661. The cubic root of 28004 is about 30.3673356447.

Adding to 28004 its reverse (40082), we get a palindrome (68086).

The spelling of 28004 in words is "twenty-eight thousand, four".