201639 has 4 divisors (see below), whose sum is σ = 268856. Its totient is φ = 134424.

The previous prime is 201629. The next prime is 201653. The reversal of 201639 is 936102.

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

It is not a de Polignac number, because 201639 - 2⁴ = 201623 is a prime.

It is a D-number.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201629) 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, 33604 + ... + 33609.

It is an arithmetic number, because the mean of its divisors is an integer number (67214).

2²⁰¹⁶³⁹ is an apocalyptic number.

201639 is a deficient number, since it is larger than the sum of its proper divisors (67217).

201639 is an equidigital number, since it uses as much as digits as its factorization.

201639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67216.

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

The square root of 201639 is about 449.0423142645. The cubic root of 201639 is about 58.6396691954.

The spelling of 201639 in words is "two hundred one thousand, six hundred thirty-nine".