28143305 has 4 divisors (see below), whose sum is σ = 33771972. Its totient is φ = 22514640.

The previous prime is 28143287. The next prime is 28143307. The reversal of 28143305 is 50334182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50334182 = 2 ⋅25167091.

It can be written as a sum of positive squares in 2 ways, for example, as 14622976 + 13520329 = 3824^2 + 3677^2 .

It is not a de Polignac number, because 28143305 - 2¹⁰ = 28142281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28143307) 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, 2814326 + ... + 2814335.

It is an arithmetic number, because the mean of its divisors is an integer number (8442993).

Almost surely, 2^28143305 is an apocalyptic number.

It is an amenable number.

28143305 is a deficient number, since it is larger than the sum of its proper divisors (5628667).

28143305 is an equidigital number, since it uses as much as digits as its factorization.

28143305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5628666.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 28143305 is about 5305.0263901323. The cubic root of 28143305 is about 304.1760615934.

Adding to 28143305 its reverse (50334182), we get a palindrome (78477487).

The spelling of 28143305 in words is "twenty-eight million, one hundred forty-three thousand, three hundred five".