81316705 has 4 divisors (see below), whose sum is σ = 97580052. Its totient is φ = 65053360.

The previous prime is 81316699. The next prime is 81316717. The reversal of 81316705 is 50761318.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9541921 + 71774784 = 3089^2 + 8472^2 .

It is not a de Polignac number, because 81316705 - 2⁵ = 81316673 is a prime.

It is a super-2 number, since 2×81316705² = 13224813024114050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8131666 + ... + 8131675.

It is an arithmetic number, because the mean of its divisors is an integer number (24395013).

Almost surely, 2^81316705 is an apocalyptic number.

It is an amenable number.

81316705 is a deficient number, since it is larger than the sum of its proper divisors (16263347).

81316705 is a wasteful number, since it uses less digits than its factorization.

81316705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16263346.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 81316705 is about 9017.5775571935. The cubic root of 81316705 is about 433.2380484118.

The spelling of 81316705 in words is "eighty-one million, three hundred sixteen thousand, seven hundred five".