81705653 has 2 divisors, whose sum is σ = 81705654. Its totient is φ = 81705652.

The previous prime is 81705623. The next prime is 81705691. The reversal of 81705653 is 35650718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43784689 + 37920964 = 6617^2 + 6158^2 .

It is a cyclic number.

It is not a de Polignac number, because 81705653 - 2¹⁴ = 81689269 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81705623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40852826 + 40852827.

It is an arithmetic number, because the mean of its divisors is an integer number (40852827).

Almost surely, 2^81705653 is an apocalyptic number.

It is an amenable number.

81705653 is a deficient number, since it is larger than the sum of its proper divisors (1).

81705653 is an equidigital number, since it uses as much as digits as its factorization.

81705653 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25200, while the sum is 35.

The square root of 81705653 is about 9039.1179326304. The cubic root of 81705653 is about 433.9276940002.

The spelling of 81705653 in words is "eighty-one million, seven hundred five thousand, six hundred fifty-three".