78685 has 4 divisors (see below), whose sum is σ = 94428. Its totient is φ = 62944.

The previous prime is 78653. The next prime is 78691. The reversal of 78685 is 58687.

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 52441 + 26244 = 229^2 + 162^2 .

It is a cyclic number.

It is not a de Polignac number, because 78685 - 2⁵ = 78653 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 78685.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7864 + ... + 7873.

It is an arithmetic number, because the mean of its divisors is an integer number (23607).

2⁷⁸⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

78685 is a deficient number, since it is larger than the sum of its proper divisors (15743).

78685 is a wasteful number, since it uses less digits than its factorization.

78685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15742.

The product of its digits is 13440, while the sum is 34.

The square root of 78685 is about 280.5084668954. The cubic root of 78685 is about 42.8512981448.

It can be divided in two parts, 7868 and 5, that multiplied together give a triangular number (39340 = T₂₈₀).

The spelling of 78685 in words is "seventy-eight thousand, six hundred eighty-five".