28643561 has 8 divisors (see below), whose sum is σ = 29694600. Its totient is φ = 27596800.

The previous prime is 28643557. The next prime is 28643599. The reversal of 28643561 is 16534682.

It can be written as a sum of positive squares in 4 ways, for example, as 2059225 + 26584336 = 1435^2 + 5156^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28643561 - 2² = 28643557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28643761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19625 + ... + 21033.

It is an arithmetic number, because the mean of its divisors is an integer number (3711825).

Almost surely, 2^28643561 is an apocalyptic number.

It is an amenable number.

28643561 is a deficient number, since it is larger than the sum of its proper divisors (1051039).

28643561 is a wasteful number, since it uses less digits than its factorization.

28643561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2139.

The product of its digits is 34560, while the sum is 35.

The square root of 28643561 is about 5351.9679558084. The cubic root of 28643561 is about 305.9677618507.

The spelling of 28643561 in words is "twenty-eight million, six hundred forty-three thousand, five hundred sixty-one".