81827191 has 2 divisors, whose sum is σ = 81827192. Its totient is φ = 81827190.

The previous prime is 81827189. The next prime is 81827203. The reversal of 81827191 is 19172818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81827191 - 2¹ = 81827189 is a prime.

Together with 81827189, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81827191.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81827131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40913595 + 40913596.

It is an arithmetic number, because the mean of its divisors is an integer number (40913596).

Almost surely, 2^81827191 is an apocalyptic number.

81827191 is a deficient number, since it is larger than the sum of its proper divisors (1).

81827191 is an equidigital number, since it uses as much as digits as its factorization.

81827191 is an evil number, because the sum of its binary digits is even.

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

The square root of 81827191 is about 9045.8383248873. The cubic root of 81827191 is about 434.1427447094.

The spelling of 81827191 in words is "eighty-one million, eight hundred twenty-seven thousand, one hundred ninety-one".