1684 has 6 divisors (see below), whose sum is σ = 2954.
Its totient is φ = 840.
The previous prime is 1669. The next prime is 1693. The reversal of 1684 is 4861.
1684 = T27 + T28 + ... +
It can be written as a sum of positive squares in only one way, i.e., 900 + 784 = 30^2 + 28^2
It is a plaindrome in base 6.
It is a nialpdrome in base 12, base 14 and base 15.
It is a zygodrome in base 6.
It is a congruent number.
It is an unprimeable number.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 207 + ... + 214.
21684 is an apocalyptic number.
1684 is the 34-th centered triangular number.
It is an amenable number.
1684 is a deficient number, since it is larger than the sum of its proper divisors (1270).
1684 is a wasteful number, since it uses less digits than its factorization.
1684 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 425 (or 423 counting only the distinct ones).
The product of its digits is 192, while the sum is 19.
The square root of 1684 is about 41.0365690574.
The cubic root of 1684 is about 11.8972712242.
It can be divided in two parts, 16 and 84, that added together give a square (100 = 102).
The spelling of 1684 in words is "one thousand, six hundred eighty-four".