28991165 has 32 divisors (see below), whose sum is σ = 41616384. Its totient is φ = 18973440.

The previous prime is 28991161. The next prime is 28991173. The reversal of 28991165 is 56119982.

It is a happy number.

It is not a de Polignac number, because 28991165 - 2² = 28991161 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 (28991161) 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 31 ways as a sum of consecutive naturals, for example, 78812 + ... + 79178.

It is an arithmetic number, because the mean of its divisors is an integer number (1300512).

Almost surely, 2^28991165 is an apocalyptic number.

It is an amenable number.

28991165 is a deficient number, since it is larger than the sum of its proper divisors (12625219).

28991165 is a wasteful number, since it uses less digits than its factorization.

28991165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477.

The product of its digits is 38880, while the sum is 41.

The square root of 28991165 is about 5384.3444354907. The cubic root of 28991165 is about 307.2004794926.

The spelling of 28991165 in words is "twenty-eight million, nine hundred ninety-one thousand, one hundred sixty-five".