28117815 has 32 divisors (see below), whose sum is σ = 51667200. Its totient is φ = 12913920.

The previous prime is 28117801. The next prime is 28117819. The reversal of 28117815 is 51871182.

It is not a de Polignac number, because 28117815 - 2⁵ = 28117783 is a prime.

It is a super-2 number, since 2×28117815² = 1581223040748450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28117819) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1350 + ... + 7619.

It is an arithmetic number, because the mean of its divisors is an integer number (1614600).

Almost surely, 2^28117815 is an apocalyptic number.

28117815 is a deficient number, since it is larger than the sum of its proper divisors (23549385).

28117815 is a wasteful number, since it uses less digits than its factorization.

28117815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9007.

The product of its digits is 4480, while the sum is 33.

The square root of 28117815 is about 5302.6234073334. The cubic root of 28117815 is about 304.0842009086.

Adding to 28117815 its reverse (51871182), we get a palindrome (79988997).

The spelling of 28117815 in words is "twenty-eight million, one hundred seventeen thousand, eight hundred fifteen".