28445 has 4 divisors (see below), whose sum is σ = 34140. Its totient is φ = 22752.

The previous prime is 28439. The next prime is 28447. The reversal of 28445 is 54482.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54482 = 2 ⋅27241.

It can be written as a sum of positive squares in 2 ways, for example, as 20164 + 8281 = 142^2 + 91^2 .

It is a cyclic number.

It is not a de Polignac number, because 28445 - 2⁴ = 28429 is a prime.

It is an Ulam number.

It is a Curzon number.

It is a nialpdrome in base 13 and base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 28445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28447) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2840 + ... + 2849.

It is an arithmetic number, because the mean of its divisors is an integer number (8535).

2²⁸⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

28445 is a deficient number, since it is larger than the sum of its proper divisors (5695).

28445 is an equidigital number, since it uses as much as digits as its factorization.

28445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5694.

The product of its digits is 1280, while the sum is 23.

The square root of 28445 is about 168.6564555539. The cubic root of 28445 is about 30.5259118686.

The spelling of 28445 in words is "twenty-eight thousand, four hundred forty-five".