87817 has 4 divisors (see below), whose sum is σ = 88596. Its totient is φ = 87040.

The previous prime is 87811. The next prime is 87833. The reversal of 87817 is 71878.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 67081 + 20736 = 259^2 + 144^2 .

It is a cyclic number.

It is not a de Polignac number, because 87817 - 2¹⁵ = 55049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 184 + ... + 457.

It is an arithmetic number, because the mean of its divisors is an integer number (22149).

2⁸⁷⁸¹⁷ is an apocalyptic number.

It is an amenable number.

87817 is a deficient number, since it is larger than the sum of its proper divisors (779).

87817 is a wasteful number, since it uses less digits than its factorization.

87817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778.

The product of its digits is 3136, while the sum is 31.

The square root of 87817 is about 296.3393325227. The cubic root of 87817 is about 44.4487479629.

Subtracting from 87817 its product of digits (3136), we obtain a square (84681 = 291²).

The spelling of 87817 in words is "eighty-seven thousand, eight hundred seventeen".