28178561 has 2 divisors, whose sum is σ = 28178562. Its totient is φ = 28178560.

The previous prime is 28178543. The next prime is 28178629. The reversal of 28178561 is 16587182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23338561 + 4840000 = 4831^2 + 2200^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28178561 is a prime.

It is not a weakly prime, because it can be changed into another prime (28178461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14089280 + 14089281.

It is an arithmetic number, because the mean of its divisors is an integer number (14089281).

Almost surely, 2^28178561 is an apocalyptic number.

It is an amenable number.

28178561 is a deficient number, since it is larger than the sum of its proper divisors (1).

28178561 is an equidigital number, since it uses as much as digits as its factorization.

28178561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26880, while the sum is 38.

The square root of 28178561 is about 5308.3482365045. The cubic root of 28178561 is about 304.3030255520.

The spelling of 28178561 in words is "twenty-eight million, one hundred seventy-eight thousand, five hundred sixty-one".