28166561 has 2 divisors, whose sum is σ = 28166562. Its totient is φ = 28166560.

The previous prime is 28166527. The next prime is 28166629. The reversal of 28166561 is 16566182.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15062161 + 13104400 = 3881^2 + 3620^2 .

It is a cyclic number.

It is not a de Polignac number, because 28166561 - 2⁶ = 28166497 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28166861) 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, 14083280 + 14083281.

It is an arithmetic number, because the mean of its divisors is an integer number (14083281).

Almost surely, 2^28166561 is an apocalyptic number.

It is an amenable number.

28166561 is a deficient number, since it is larger than the sum of its proper divisors (1).

28166561 is an equidigital number, since it uses as much as digits as its factorization.

28166561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 35.

The square root of 28166561 is about 5307.2178210433. The cubic root of 28166561 is about 304.2598230290.

The spelling of 28166561 in words is "twenty-eight million, one hundred sixty-six thousand, five hundred sixty-one".