28513321 has 4 divisors (see below), whose sum is σ = 28527444. Its totient is φ = 28499200.

The previous prime is 28513313. The next prime is 28513339. The reversal of 28513321 is 12331582.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7901721 + 20611600 = 2811^2 + 4540^2 .

It is a cyclic number.

It is not a de Polignac number, because 28513321 - 2³ = 28513313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28513021) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3400 + ... + 8281.

It is an arithmetic number, because the mean of its divisors is an integer number (7131861).

Almost surely, 2^28513321 is an apocalyptic number.

It is an amenable number.

28513321 is a deficient number, since it is larger than the sum of its proper divisors (14123).

28513321 is a wasteful number, since it uses less digits than its factorization.

28513321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14122.

The product of its digits is 1440, while the sum is 25.

The square root of 28513321 is about 5339.7866062231. The cubic root of 28513321 is about 305.5033201629.

The spelling of 28513321 in words is "twenty-eight million, five hundred thirteen thousand, three hundred twenty-one".