28120217 has 2 divisors, whose sum is σ = 28120218. Its totient is φ = 28120216.

The previous prime is 28120201. The next prime is 28120229. The reversal of 28120217 is 71202182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25361296 + 2758921 = 5036^2 + 1661^2 .

It is a cyclic number.

It is not a de Polignac number, because 28120217 - 2⁴ = 28120201 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 28120192 and 28120201.

It is not a weakly prime, because it can be changed into another prime (28120717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14060108 + 14060109.

It is an arithmetic number, because the mean of its divisors is an integer number (14060109).

Almost surely, 2^28120217 is an apocalyptic number.

It is an amenable number.

28120217 is a deficient number, since it is larger than the sum of its proper divisors (1).

28120217 is an equidigital number, since it uses as much as digits as its factorization.

28120217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 28120217 is about 5302.8498941607. The cubic root of 28120217 is about 304.0928595882.

Adding to 28120217 its reverse (71202182), we get a palindrome (99322399).

The spelling of 28120217 in words is "twenty-eight million, one hundred twenty thousand, two hundred seventeen".