28917209 has 8 divisors (see below), whose sum is σ = 29376000. Its totient is φ = 28462000.

The previous prime is 28917197. The next prime is 28917211. The reversal of 28917209 is 90271982.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28917209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28917269) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18542 + ... + 20040.

It is an arithmetic number, because the mean of its divisors is an integer number (3672000).

Almost surely, 2^28917209 is an apocalyptic number.

It is an amenable number.

28917209 is a deficient number, since it is larger than the sum of its proper divisors (458791).

28917209 is a wasteful number, since it uses less digits than its factorization.

28917209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1791.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 28917209 is about 5377.4723616212. The cubic root of 28917209 is about 306.9390358774.

The spelling of 28917209 in words is "twenty-eight million, nine hundred seventeen thousand, two hundred nine".