28691289 has 24 divisors (see below), whose sum is σ = 45961344. Its totient is φ = 17100000.

The previous prime is 28691261. The next prime is 28691297. The reversal of 28691289 is 98219682.

28691289 is a `hidden beast` number, since 286 + 91 + 289 = 666.

It is not a de Polignac number, because 28691289 - 2⁷ = 28691161 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28691219) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3664 + ... + 8414.

It is an arithmetic number, because the mean of its divisors is an integer number (1915056).

Almost surely, 2^28691289 is an apocalyptic number.

It is an amenable number.

28691289 is a deficient number, since it is larger than the sum of its proper divisors (17270055).

28691289 is a wasteful number, since it uses less digits than its factorization.

28691289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4829 (or 4826 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 28691289 is about 5356.4250204777. The cubic root of 28691289 is about 306.1376095156.

The spelling of 28691289 in words is "twenty-eight million, six hundred ninety-one thousand, two hundred eighty-nine".