28290509 has 4 divisors (see below), whose sum is σ = 30466716. Its totient is φ = 26114304.

The previous prime is 28290463. The next prime is 28290511. The reversal of 28290509 is 90509282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90509282 = 2 ⋅45254641.

It can be written as a sum of positive squares in 2 ways, for example, as 17825284 + 10465225 = 4222^2 + 3235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28290509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28290539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1088084 + ... + 1088109.

It is an arithmetic number, because the mean of its divisors is an integer number (7616679).

Almost surely, 2^28290509 is an apocalyptic number.

It is an amenable number.

28290509 is a deficient number, since it is larger than the sum of its proper divisors (2176207).

28290509 is a wasteful number, since it uses less digits than its factorization.

28290509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2176206.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 28290509 is about 5318.8823074026. The cubic root of 28290509 is about 304.7054721934.

The spelling of 28290509 in words is "twenty-eight million, two hundred ninety thousand, five hundred nine".