27181991 has 2 divisors, whose sum is σ = 27181992. Its totient is φ = 27181990.

The previous prime is 27181981. The next prime is 27181993. The reversal of 27181991 is 19918172.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 27181991 - 2¹⁸ = 26919847 is a prime.

It is a Sophie Germain prime.

Together with 27181993, 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 (27181993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13590995 + 13590996.

It is an arithmetic number, because the mean of its divisors is an integer number (13590996).

Almost surely, 2^27181991 is an apocalyptic number.

27181991 is a deficient number, since it is larger than the sum of its proper divisors (1).

27181991 is an equidigital number, since it uses as much as digits as its factorization.

27181991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9072, while the sum is 38.

The square root of 27181991 is about 5213.6351042243. The cubic root of 27181991 is about 300.6725319500.

The spelling of 27181991 in words is "twenty-seven million, one hundred eighty-one thousand, nine hundred ninety-one".