81867717 has 12 divisors (see below), whose sum is σ = 121449900. Its totient is φ = 53103168.

The previous prime is 81867707. The next prime is 81867719. The reversal of 81867717 is 71776818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 39955041 + 41912676 = 6321^2 + 6474^2 .

It is not a de Polignac number, because 81867717 - 2⁷ = 81867589 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81867719) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 122592 + ... + 123257.

It is an arithmetic number, because the mean of its divisors is an integer number (10120825).

Almost surely, 2^81867717 is an apocalyptic number.

It is an amenable number.

81867717 is a deficient number, since it is larger than the sum of its proper divisors (39582183).

81867717 is a wasteful number, since it uses less digits than its factorization.

81867717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245892 (or 245889 counting only the distinct ones).

The product of its digits is 131712, while the sum is 45.

The square root of 81867717 is about 9048.0780832175. The cubic root of 81867717 is about 434.2144045285.

The spelling of 81867717 in words is "eighty-one million, eight hundred sixty-seven thousand, seven hundred seventeen".