27978121 has 2 divisors, whose sum is σ = 27978122. Its totient is φ = 27978120.

The previous prime is 27978109. The next prime is 27978149. The reversal of 27978121 is 12187972.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17808400 + 10169721 = 4220^2 + 3189^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27978121 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (27978191) 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, 13989060 + 13989061.

It is an arithmetic number, because the mean of its divisors is an integer number (13989061).

Almost surely, 2^27978121 is an apocalyptic number.

It is an amenable number.

27978121 is a deficient number, since it is larger than the sum of its proper divisors (1).

27978121 is an equidigital number, since it uses as much as digits as its factorization.

27978121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 37.

The square root of 27978121 is about 5289.4348469378. The cubic root of 27978121 is about 303.5797842801.

It can be divided in two parts, 279 and 78121, that added together give a square (78400 = 280²).

The spelling of 27978121 in words is "twenty-seven million, nine hundred seventy-eight thousand, one hundred twenty-one".