28216217 has 8 divisors (see below), whose sum is σ = 29305800. Its totient is φ = 27134464.

The previous prime is 28216211. The next prime is 28216229. The reversal of 28216217 is 71261282.

It can be written as a sum of positive squares in 4 ways, for example, as 1290496 + 26925721 = 1136^2 + 5189^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28216217 - 2⁸ = 28215961 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28216217.

It is not an unprimeable number, because it can be changed into a prime (28216211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5993 + ... + 9609.

It is an arithmetic number, because the mean of its divisors is an integer number (3663225).

Almost surely, 2^28216217 is an apocalyptic number.

It is an amenable number.

28216217 is a deficient number, since it is larger than the sum of its proper divisors (1089583).

28216217 is a wasteful number, since it uses less digits than its factorization.

28216217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3915.

The product of its digits is 2688, while the sum is 29.

The square root of 28216217 is about 5311.8939183685. The cubic root of 28216217 is about 304.4385154875.

Adding to 28216217 its reverse (71261282), we get a palindrome (99477499).

The spelling of 28216217 in words is "twenty-eight million, two hundred sixteen thousand, two hundred seventeen".