28644561 has 24 divisors (see below), whose sum is σ = 45658080. Its totient is φ = 17160000.

The previous prime is 28644557. The next prime is 28644569. The reversal of 28644561 is 16544682.

28644561 is a `hidden beast` number, since 2 + 8 + 644 + 5 + 6 + 1 = 666.

It is not a de Polignac number, because 28644561 - 2² = 28644557 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28644569) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7186 + ... + 10436.

It is an arithmetic number, because the mean of its divisors is an integer number (1902420).

Almost surely, 2^28644561 is an apocalyptic number.

It is an amenable number.

28644561 is a deficient number, since it is larger than the sum of its proper divisors (17013519).

28644561 is a wasteful number, since it uses less digits than its factorization.

28644561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3357 (or 3354 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 28644561 is about 5352.0613785718. The cubic root of 28644561 is about 305.9713224439.

The spelling of 28644561 in words is "twenty-eight million, six hundred forty-four thousand, five hundred sixty-one".