28891117 has 4 divisors (see below), whose sum is σ = 29671996. Its totient is φ = 28110240.

The previous prime is 28891111. The next prime is 28891123. The reversal of 28891117 is 71119882.

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

It is an interprime number because it is at equal distance from previous prime (28891111) and next prime (28891123).

It can be written as a sum of positive squares in 2 ways, for example, as 10666756 + 18224361 = 3266^2 + 4269^2 .

It is a cyclic number.

It is not a de Polignac number, because 28891117 - 2²³ = 20502509 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 780841 = 28891117 / (2 + 8 + 8 + 9 + 1 + 1 + 1 + 7).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28891111) 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, 390384 + ... + 390457.

It is an arithmetic number, because the mean of its divisors is an integer number (7417999).

Almost surely, 2^28891117 is an apocalyptic number.

It is an amenable number.

28891117 is a deficient number, since it is larger than the sum of its proper divisors (780879).

28891117 is an equidigital number, since it uses as much as digits as its factorization.

28891117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780878.

The product of its digits is 8064, while the sum is 37.

The square root of 28891117 is about 5375.0457672470. The cubic root of 28891117 is about 306.8466910586.

The spelling of 28891117 in words is "twenty-eight million, eight hundred ninety-one thousand, one hundred seventeen".