27806981 has 2 divisors, whose sum is σ = 27806982. Its totient is φ = 27806980.

The previous prime is 27806971. The next prime is 27806983. The reversal of 27806981 is 18960872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20784481 + 7022500 = 4559^2 + 2650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27806981 is a prime.

It is a super-2 number, since 2×27806981² = 1546456384668722, which contains 22 as substring.

Together with 27806983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27806983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13903490 + 13903491.

It is an arithmetic number, because the mean of its divisors is an integer number (13903491).

Almost surely, 2^27806981 is an apocalyptic number.

It is an amenable number.

27806981 is a deficient number, since it is larger than the sum of its proper divisors (1).

27806981 is an equidigital number, since it uses as much as digits as its factorization.

27806981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 27806981 is about 5273.2325000895. The cubic root of 27806981 is about 302.9595265208.

The spelling of 27806981 in words is "twenty-seven million, eight hundred six thousand, nine hundred eighty-one".