81704191 has 2 divisors, whose sum is σ = 81704192. Its totient is φ = 81704190.

The previous prime is 81704153. The next prime is 81704201. The reversal of 81704191 is 19140718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81704191 - 2⁹ = 81703679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81704131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40852095 + 40852096.

It is an arithmetic number, because the mean of its divisors is an integer number (40852096).

Almost surely, 2^81704191 is an apocalyptic number.

81704191 is a deficient number, since it is larger than the sum of its proper divisors (1).

81704191 is an equidigital number, since it uses as much as digits as its factorization.

81704191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 81704191 is about 9039.0370615459. The cubic root of 81704191 is about 433.9251058232.

The spelling of 81704191 in words is "eighty-one million, seven hundred four thousand, one hundred ninety-one".