28091217 has 16 divisors (see below), whose sum is σ = 46697472. Its totient is φ = 14592720.

The previous prime is 28091213. The next prime is 28091249. The reversal of 28091217 is 71219082.

It is not a de Polignac number, because 28091217 - 2² = 28091213 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28091213) 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, 60573 + ... + 61034.

It is an arithmetic number, because the mean of its divisors is an integer number (2918592).

Almost surely, 2^28091217 is an apocalyptic number.

It is an amenable number.

28091217 is a deficient number, since it is larger than the sum of its proper divisors (18606255).

28091217 is a wasteful number, since it uses less digits than its factorization.

28091217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121628.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 28091217 is about 5300.1148100772. The cubic root of 28091217 is about 303.9882880125.

The spelling of 28091217 in words is "twenty-eight million, ninety-one thousand, two hundred seventeen".