28509997 has 8 divisors (see below), whose sum is σ = 29140992. Its totient is φ = 27884400.

The previous prime is 28509991. The next prime is 28510007. The reversal of 28509997 is 79990582.

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 28509997 - 2¹⁹ = 27985709 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28509997.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28509991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10428 + ... + 12874.

It is an arithmetic number, because the mean of its divisors is an integer number (3642624).

Almost surely, 2^28509997 is an apocalyptic number.

It is an amenable number.

28509997 is a deficient number, since it is larger than the sum of its proper divisors (630995).

28509997 is a wasteful number, since it uses less digits than its factorization.

28509997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2699.

The product of its (nonzero) digits is 408240, while the sum is 49.

The square root of 28509997 is about 5339.4753487585. The cubic root of 28509997 is about 305.4914481388.

The spelling of 28509997 in words is "twenty-eight million, five hundred nine thousand, nine hundred ninety-seven".