86781 has 4 divisors (see below), whose sum is σ = 115712. Its totient is φ = 57852.

The previous prime is 86771. The next prime is 86783. The reversal of 86781 is 18768.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 86781 - 2⁹ = 86269 is a prime.

It is a super-2 number, since 2×86781² = 15061883922, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (86783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14461 + ... + 14466.

It is an arithmetic number, because the mean of its divisors is an integer number (28928).

2⁸⁶⁷⁸¹ is an apocalyptic number.

It is an amenable number.

86781 is a deficient number, since it is larger than the sum of its proper divisors (28931).

86781 is a wasteful number, since it uses less digits than its factorization.

86781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28930.

The product of its digits is 2688, while the sum is 30.

The square root of 86781 is about 294.5861503873. The cubic root of 86781 is about 44.2732649214.

The spelling of 86781 in words is "eighty-six thousand, seven hundred eighty-one".