28491565 has 4 divisors (see below), whose sum is σ = 34189884. Its totient is φ = 22793248.

The previous prime is 28491563. The next prime is 28491569. The reversal of 28491565 is 56519482.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13638249 + 14853316 = 3693^2 + 3854^2 .

It is a cyclic number.

It is not a de Polignac number, because 28491565 - 2¹ = 28491563 is a prime.

It is a super-2 number, since 2×28491565² = 1623538552298450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28491563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2849152 + ... + 2849161.

It is an arithmetic number, because the mean of its divisors is an integer number (8547471).

Almost surely, 2^28491565 is an apocalyptic number.

It is an amenable number.

28491565 is a deficient number, since it is larger than the sum of its proper divisors (5698319).

28491565 is an equidigital number, since it uses as much as digits as its factorization.

28491565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5698318.

The product of its digits is 86400, while the sum is 40.

The square root of 28491565 is about 5337.7490574211. The cubic root of 28491565 is about 305.4255995142.

The spelling of 28491565 in words is "twenty-eight million, four hundred ninety-one thousand, five hundred sixty-five".