2005639 has 4 divisors (see below), whose sum is σ = 2012400. Its totient is φ = 1998880.

The previous prime is 2005613. The next prime is 2005667. The reversal of 2005639 is 9365002.

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 2005639 - 2¹¹ = 2003591 is a prime.

It is a Duffinian number.

2005639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2005039) 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, 2914 + ... + 3535.

It is an arithmetic number, because the mean of its divisors is an integer number (503100).

2^2005639 is an apocalyptic number.

2005639 is a deficient number, since it is larger than the sum of its proper divisors (6761).

2005639 is an equidigital number, since it uses as much as digits as its factorization.

2005639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6760.

The product of its (nonzero) digits is 1620, while the sum is 25.

The square root of 2005639 is about 1416.2058466198. The cubic root of 2005639 is about 126.1104054563.

The spelling of 2005639 in words is "two million, five thousand, six hundred thirty-nine".