27181981 has 2 divisors, whose sum is σ = 27181982. Its totient is φ = 27181980.

The previous prime is 27181969. The next prime is 27181991. The reversal of 27181981 is 18918172.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23609881 + 3572100 = 4859^2 + 1890^2 .

It is a cyclic number.

It is not a de Polignac number, because 27181981 - 2¹⁹ = 26657693 is a prime.

It is a super-2 number, since 2×27181981² = 1477720182168722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 27181981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27181901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13590990 + 13590991.

It is an arithmetic number, because the mean of its divisors is an integer number (13590991).

Almost surely, 2^27181981 is an apocalyptic number.

It is an amenable number.

27181981 is a deficient number, since it is larger than the sum of its proper divisors (1).

27181981 is an equidigital number, since it uses as much as digits as its factorization.

27181981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 37.

The square root of 27181981 is about 5213.6341452004. The cubic root of 27181981 is about 300.6724950785.

The spelling of 27181981 in words is "twenty-seven million, one hundred eighty-one thousand, nine hundred eighty-one".