28515217 has 2 divisors, whose sum is σ = 28515218. Its totient is φ = 28515216.

The previous prime is 28515209. The next prime is 28515247. The reversal of 28515217 is 71251582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27973521 + 541696 = 5289^2 + 736^2 .

It is a cyclic number.

It is not a de Polignac number, because 28515217 - 2³ = 28515209 is a prime.

It is not a weakly prime, because it can be changed into another prime (28515247) 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, 14257608 + 14257609.

It is an arithmetic number, because the mean of its divisors is an integer number (14257609).

Almost surely, 2^28515217 is an apocalyptic number.

It is an amenable number.

28515217 is a deficient number, since it is larger than the sum of its proper divisors (1).

28515217 is an equidigital number, since it uses as much as digits as its factorization.

28515217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5600, while the sum is 31.

The square root of 28515217 is about 5339.9641384564. The cubic root of 28515217 is about 305.5100915179.

Adding to 28515217 its reverse (71251582), we get a palindrome (99766799).

The spelling of 28515217 in words is "twenty-eight million, five hundred fifteen thousand, two hundred seventeen".