78689 has 4 divisors (see below), whose sum is σ = 84756. Its totient is φ = 72624.

The previous prime is 78653. The next prime is 78691. The reversal of 78689 is 98687.

78689 = 42² + 43² + ... + 67².

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 8464 + 70225 = 92^2 + 265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78689 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78649) 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, 3014 + ... + 3039.

It is an arithmetic number, because the mean of its divisors is an integer number (21189).

2⁷⁸⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

78689 is a deficient number, since it is larger than the sum of its proper divisors (6067).

78689 is a wasteful number, since it uses less digits than its factorization.

78689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6066.

The product of its digits is 24192, while the sum is 38.

The square root of 78689 is about 280.5155967143. The cubic root of 78689 is about 42.8520242564.

It can be divided in two parts, 78 and 689, that added together give a palindrome (767).

The spelling of 78689 in words is "seventy-eight thousand, six hundred eighty-nine".