1687 has 4 divisors (see below), whose sum is σ = 1936. Its totient is φ = 1440.

The previous prime is 1669. The next prime is 1693. The reversal of 1687 is 7861.

1687 = T₈ + T₉ + ... + T₂₁.

1687 is nontrivially palindromic in base 15.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7861 = 7 ⋅1123.

It is a cyclic number.

It is not a de Polignac number, because 1687 - 2⁷ = 1559 is a prime.

It is a Duffinian number.

1687 is a nontrivial repdigit in base 15.

It is a plaindrome in base 15.

It is a nialpdrome in base 12, base 14 and base 15.

It is a zygodrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1607) 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, 114 + ... + 127.

It is an arithmetic number, because the mean of its divisors is an integer number (484).

2¹⁶⁸⁷ is an apocalyptic number.

1687 is a deficient number, since it is larger than the sum of its proper divisors (249).

1687 is an equidigital number, since it uses as much as digits as its factorization.

1687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248.

The product of its digits is 336, while the sum is 22.

The square root of 1687 is about 41.0731055558. The cubic root of 1687 is about 11.9043319210.

It can be divided in two parts, 168 and 7, that multiplied together give a triangular number (1176 = T₄₈).

The spelling of 1687 in words is "one thousand, six hundred eighty-seven".