27805621 has 2 divisors, whose sum is σ = 27805622. Its totient is φ = 27805620.

The previous prime is 27805619. The next prime is 27805633. The reversal of 27805621 is 12650872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16313521 + 11492100 = 4039^2 + 3390^2 .

It is a cyclic number.

It is not a de Polignac number, because 27805621 - 2¹ = 27805619 is a prime.

Together with 27805619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27800621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13902810 + 13902811.

It is an arithmetic number, because the mean of its divisors is an integer number (13902811).

Almost surely, 2^27805621 is an apocalyptic number.

It is an amenable number.

27805621 is a deficient number, since it is larger than the sum of its proper divisors (1).

27805621 is an equidigital number, since it uses as much as digits as its factorization.

27805621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 27805621 is about 5273.1035453516. The cubic root of 27805621 is about 302.9545873333.

The spelling of 27805621 in words is "twenty-seven million, eight hundred five thousand, six hundred twenty-one".