28005009 has 16 divisors (see below), whose sum is σ = 38459904. Its totient is φ = 18115200.

The previous prime is 28004987. The next prime is 28005011. The reversal of 28005009 is 90050082.

It is not a de Polignac number, because 28005009 - 2⁹ = 28004497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28005009.

It is not an unprimeable number, because it can be changed into a prime (28005079) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26919 + ... + 27939.

It is an arithmetic number, because the mean of its divisors is an integer number (2403744).

Almost surely, 2^28005009 is an apocalyptic number.

It is an amenable number.

28005009 is a deficient number, since it is larger than the sum of its proper divisors (10454895).

28005009 is a wasteful number, since it uses less digits than its factorization.

28005009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 28005009 is about 5291.9759069746. The cubic root of 28005009 is about 303.6770035771.

The spelling of 28005009 in words is "twenty-eight million, five thousand, nine".