1639 has 4 divisors (see below), whose sum is σ = 1800.
Its totient is φ = 1480.
The previous prime is 1637. The next prime is 1657. The reversal of 1639 is 9361.
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 1639 - 21 = 1637 is a prime.
It is a Duffinian number.
1639 is a lucky number.
It is a plaindrome in base 16.
It is a nialpdrome in base 9, base 13, base 14 and base 15.
It is a zygodrome in base 2.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1637) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64 + ... + 85.
It is an arithmetic number, because the mean of its divisors is an integer number (450).
21639 is an apocalyptic number.
1639 is the 22-nd nonagonal number.
1639 is a deficient number, since it is larger than the sum of its proper divisors (161).
1639 is a wasteful number, since it uses less digits than its factorization.
1639 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 160.
The product of its digits is 162, while the sum is 19.
The square root of 1639 is about 40.4845649600.
The cubic root of 1639 is about 11.7903396948.
The spelling of 1639 in words is "one thousand, six hundred thirty-nine".