28304561 has 4 divisors (see below), whose sum is σ = 28320612. Its totient is φ = 28288512.

The previous prime is 28304557. The next prime is 28304567. The reversal of 28304561 is 16540382.

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 13366336 + 14938225 = 3656^2 + 3865^2 .

It is a cyclic number.

It is not a de Polignac number, because 28304561 - 2² = 28304557 is a prime.

It is a super-2 number, since 2×28304561² = 1602296346805442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28304567) 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, 5000 + ... + 9033.

It is an arithmetic number, because the mean of its divisors is an integer number (7080153).

Almost surely, 2^28304561 is an apocalyptic number.

It is an amenable number.

28304561 is a deficient number, since it is larger than the sum of its proper divisors (16051).

28304561 is a wasteful number, since it uses less digits than its factorization.

28304561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16050.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 28304561 is about 5320.2030976270. The cubic root of 28304561 is about 304.7559132863.

The spelling of 28304561 in words is "twenty-eight million, three hundred four thousand, five hundred sixty-one".