81766985 has 8 divisors (see below), whose sum is σ = 98170056. Its totient is φ = 65380480.

The previous prime is 81766973. The next prime is 81766987. The reversal of 81766985 is 58966718.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 38588944 + 43178041 = 6212^2 + 6571^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81766985 - 2¹⁶ = 81701449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81766987) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13775 + ... + 18795.

It is an arithmetic number, because the mean of its divisors is an integer number (12271257).

Almost surely, 2^81766985 is an apocalyptic number.

It is an amenable number.

81766985 is a deficient number, since it is larger than the sum of its proper divisors (16403071).

81766985 is a wasteful number, since it uses less digits than its factorization.

81766985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8283.

The product of its digits is 725760, while the sum is 50.

The square root of 81766985 is about 9042.5098838763. The cubic root of 81766985 is about 434.0362421687.

The spelling of 81766985 in words is "eighty-one million, seven hundred sixty-six thousand, nine hundred eighty-five".