9639 has 20 divisors (see below), whose sum is σ = 17424. Its totient is φ = 5184.

The previous prime is 9631. The next prime is 9643. The reversal of 9639 is 9369.

It is not a de Polignac number, because 9639 - 2³ = 9631 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

Its product of digits (1458) is a multiple of the sum of its prime divisors (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9631) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 559 + ... + 575.

2⁹⁶³⁹ is an apocalyptic number.

9639 is a deficient number, since it is larger than the sum of its proper divisors (7785).

9639 is a wasteful number, since it uses less digits than its factorization.

9639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36 (or 27 counting only the distinct ones).

The product of its digits is 1458, while the sum is 27.

The square root of 9639 is about 98.1784090317. The cubic root of 9639 is about 21.2819128343.

The spelling of 9639 in words is "nine thousand, six hundred thirty-nine".