2001639 has 8 divisors (see below), whose sum is σ = 2755072. Its totient is φ = 1291320.

The previous prime is 2001619. The next prime is 2001641. The reversal of 2001639 is 9361002.

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

It is not a de Polignac number, because 2001639 - 2⁷ = 2001511 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 (2001619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10669 + ... + 10854.

It is an arithmetic number, because the mean of its divisors is an integer number (344384).

2^2001639 is an apocalyptic number.

2001639 is a deficient number, since it is larger than the sum of its proper divisors (753433).

2001639 is a wasteful number, since it uses less digits than its factorization.

2001639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21557.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 2001639 is about 1414.7929177092. The cubic root of 2001639 is about 126.0265124356.

The spelling of 2001639 in words is "two million, one thousand, six hundred thirty-nine".