8639 has 4 divisors (see below), whose sum is σ = 8856. Its totient is φ = 8424.

The previous prime is 8629. The next prime is 8641. The reversal of 8639 is 9368.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 8639 - 2⁴ = 8623 is a prime.

It is an Ulam number.

It is a Duffinian number.

Its product of digits (1296) is a multiple of the sum of its prime divisors (216).

It is a plaindrome in base 12.

It is a nialpdrome in base 11 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8609) 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, 29 + ... + 134.

It is an arithmetic number, because the mean of its divisors is an integer number (2214).

2⁸⁶³⁹ is an apocalyptic number.

8639 is a deficient number, since it is larger than the sum of its proper divisors (217).

8639 is a wasteful number, since it uses less digits than its factorization.

8639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216.

The product of its digits is 1296, while the sum is 26.

The square root of 8639 is about 92.9462210098. The cubic root of 8639 is about 20.5189196740.

Subtracting 8639 from its reverse (9368), we obtain a 6-th power (729 = 3⁶).

It can be divided in two parts, 86 and 39, that added together give a cube (125 = 5³).

The spelling of 8639 in words is "eight thousand, six hundred thirty-nine".