27666821 has 24 divisors (see below), whose sum is σ = 35000280. Its totient is φ = 21805056.

The previous prime is 27666757. The next prime is 27666833. The reversal of 27666821 is 12866672.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1768900 + 25897921 = 1330^2 + 5089^2 .

It is not a de Polignac number, because 27666821 - 2⁶ = 27666757 is a prime.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27666721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 107525 + ... + 107781.

It is an arithmetic number, because the mean of its divisors is an integer number (1458345).

Almost surely, 2^27666821 is an apocalyptic number.

It is an amenable number.

27666821 is a deficient number, since it is larger than the sum of its proper divisors (7333459).

27666821 is an equidigital number, since it uses as much as digits as its factorization.

27666821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310 (or 277 counting only the distinct ones).

The product of its digits is 48384, while the sum is 38.

The square root of 27666821 is about 5259.9259500491. The cubic root of 27666821 is about 302.4496503410.

The spelling of 27666821 in words is "twenty-seven million, six hundred sixty-six thousand, eight hundred twenty-one".