28289909 has 8 divisors (see below), whose sum is σ = 29152152. Its totient is φ = 27440640.

The previous prime is 28289903. The next prime is 28289927. The reversal of 28289909 is 90998282.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 305809 + 27984100 = 553^2 + 5290^2 .

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 28289909 - 2¹⁶ = 28224373 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 (28289903) 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 7 ways as a sum of consecutive naturals, for example, 1277 + ... + 7629.

It is an arithmetic number, because the mean of its divisors is an integer number (3644019).

Almost surely, 2^28289909 is an apocalyptic number.

It is an amenable number.

28289909 is a deficient number, since it is larger than the sum of its proper divisors (862243).

28289909 is an equidigital number, since it uses as much as digits as its factorization.

28289909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6487.

The product of its (nonzero) digits is 186624, while the sum is 47.

The square root of 28289909 is about 5318.8259042762. The cubic root of 28289909 is about 304.7033180602.

The spelling of 28289909 in words is "twenty-eight million, two hundred eighty-nine thousand, nine hundred nine".