78639 has 8 divisors (see below), whose sum is σ = 114432. Its totient is φ = 47640.

The previous prime is 78623. The next prime is 78643. The reversal of 78639 is 93687.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78639 - 2^{4} = 78623 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 2383 = 78639 / (7 + 8 + 6 + 3 + 9).

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 7 ways as a sum of consecutive naturals, for example, 1159 + ... + 1224.

It is an arithmetic number, because the mean of its divisors is an integer number (14304).

2^{78639} is an apocalyptic number.

78639 is a deficient number, since it is larger than the sum of its proper divisors (35793).

78639 is a wasteful number, since it uses less digits than its factorization.

78639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2397.

The product of its digits is 9072, while the sum is 33.

The square root of 78639 is about 280.4264609483. The cubic root of 78639 is about 42.8429460914.

Subtracting from 78639 its sum of digits (33), we obtain a triangular number (78606 = T_{396}).

It can be divided in two parts, 78 and 639, that added together give a palindrome (717).

The spelling of 78639 in words is "seventy-eight thousand, six hundred thirty-nine".

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