28165021 has 2 divisors, whose sum is σ = 28165022. Its totient is φ = 28165020.

The previous prime is 28165013. The next prime is 28165091. The reversal of 28165021 is 12056182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 7562500 = 4539^2 + 2750^2 .

It is a cyclic number.

It is not a de Polignac number, because 28165021 - 2³ = 28165013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28165091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14082510 + 14082511.

It is an arithmetic number, because the mean of its divisors is an integer number (14082511).

Almost surely, 2^28165021 is an apocalyptic number.

It is an amenable number.

28165021 is a deficient number, since it is larger than the sum of its proper divisors (1).

28165021 is an equidigital number, since it uses as much as digits as its factorization.

28165021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 28165021 is about 5307.0727336263. The cubic root of 28165021 is about 304.2542778169.

The spelling of 28165021 in words is "twenty-eight million, one hundred sixty-five thousand, twenty-one".