27991289 has 4 divisors (see below), whose sum is σ = 28179300. Its totient is φ = 27803280.

The previous prime is 27991267. The next prime is 27991291. The reversal of 27991289 is 98219972.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1776889 + 26214400 = 1333^2 + 5120^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27991289 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (27991219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93782 + ... + 94079.

It is an arithmetic number, because the mean of its divisors is an integer number (7044825).

Almost surely, 2^27991289 is an apocalyptic number.

It is an amenable number.

27991289 is a deficient number, since it is larger than the sum of its proper divisors (188011).

27991289 is a wasteful number, since it uses less digits than its factorization.

27991289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188010.

The product of its digits is 163296, while the sum is 47.

The square root of 27991289 is about 5290.6794459691. The cubic root of 27991289 is about 303.6274037708.

The spelling of 27991289 in words is "twenty-seven million, nine hundred ninety-one thousand, two hundred eighty-nine".