81765305 has 4 divisors (see below), whose sum is σ = 98118372. Its totient is φ = 65412240.

The previous prime is 81765293. The next prime is 81765311. The reversal of 81765305 is 50356718.

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 10936249 + 70829056 = 3307^2 + 8416^2 .

It is not a de Polignac number, because 81765305 - 2¹⁰ = 81764281 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 8176526 + ... + 8176535.

It is an arithmetic number, because the mean of its divisors is an integer number (24529593).

Almost surely, 2^81765305 is an apocalyptic number.

It is an amenable number.

81765305 is a deficient number, since it is larger than the sum of its proper divisors (16353067).

81765305 is a wasteful number, since it uses less digits than its factorization.

81765305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16353066.

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

The square root of 81765305 is about 9042.4169888366. The cubic root of 81765305 is about 434.0332695513.

The spelling of 81765305 in words is "eighty-one million, seven hundred sixty-five thousand, three hundred five".