28305287 has 4 divisors (see below), whose sum is σ = 28323456. Its totient is φ = 28287120.

The previous prime is 28305227. The next prime is 28305313. The reversal of 28305287 is 78250382.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 28305287 - 2¹⁴ = 28288903 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 (28305217) 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, 6503 + ... + 9944.

It is an arithmetic number, because the mean of its divisors is an integer number (7080864).

Almost surely, 2^28305287 is an apocalyptic number.

28305287 is a deficient number, since it is larger than the sum of its proper divisors (18169).

28305287 is a wasteful number, since it uses less digits than its factorization.

28305287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18168.

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 28305287 is about 5320.2713276674. The cubic root of 28305287 is about 304.7585188841.

The spelling of 28305287 in words is "twenty-eight million, three hundred five thousand, two hundred eighty-seven".