81706393 has 2 divisors, whose sum is σ = 81706394. Its totient is φ = 81706392.

The previous prime is 81706381. The next prime is 81706409. The reversal of 81706393 is 39360718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80946009 + 760384 = 8997^2 + 872^2 .

It is a cyclic number.

It is not a de Polignac number, because 81706393 - 2²¹ = 79609241 is a prime.

It is not a weakly prime, because it can be changed into another prime (81706363) 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, 40853196 + 40853197.

It is an arithmetic number, because the mean of its divisors is an integer number (40853197).

Almost surely, 2^81706393 is an apocalyptic number.

It is an amenable number.

81706393 is a deficient number, since it is larger than the sum of its proper divisors (1).

81706393 is an equidigital number, since it uses as much as digits as its factorization.

81706393 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 81706393 is about 9039.1588657352. The cubic root of 81706393 is about 433.9290040096.

The spelling of 81706393 in words is "eighty-one million, seven hundred six thousand, three hundred ninety-three".