28009917 has 24 divisors (see below), whose sum is σ = 44402904. Its totient is φ = 16907904.

The previous prime is 28009913. The next prime is 28009937. The reversal of 28009917 is 71990082.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 68121 + 27941796 = 261^2 + 5286^2 .

It is not a de Polignac number, because 28009917 - 2² = 28009913 is a prime.

It is a super-4 number, since 4×28009917⁴ (a number of 31 digits) contains 4444 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28009913) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3943 + ... + 8459.

It is an arithmetic number, because the mean of its divisors is an integer number (1850121).

Almost surely, 2^28009917 is an apocalyptic number.

It is an amenable number.

28009917 is a deficient number, since it is larger than the sum of its proper divisors (16392987).

28009917 is a wasteful number, since it uses less digits than its factorization.

28009917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4589 (or 4586 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 28009917 is about 5292.4396075912. The cubic root of 28009917 is about 303.6947427808.

Adding to 28009917 its reverse (71990082), we get a palindrome (99999999).

The spelling of 28009917 in words is "twenty-eight million, nine thousand, nine hundred seventeen".