1687321 has 8 divisors (see below), whose sum is σ = 1736000. Its totient is φ = 1639440.

The previous prime is 1687319. The next prime is 1687327. The reversal of 1687321 is 1237861.

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

It is a cyclic number.

It is not a de Polignac number, because 1687321 - 2¹ = 1687319 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1687321.

It is not an unprimeable number, because it can be changed into a prime (1687327) 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, 8380 + ... + 8578.

It is an arithmetic number, because the mean of its divisors is an integer number (217000).

2^1687321 is an apocalyptic number.

It is an amenable number.

1687321 is a deficient number, since it is larger than the sum of its proper divisors (48679).

1687321 is a wasteful number, since it uses less digits than its factorization.

1687321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399.

The product of its digits is 2016, while the sum is 28.

The square root of 1687321 is about 1298.9692067174. The cubic root of 1687321 is about 119.0508691963.

The spelling of 1687321 in words is "one million, six hundred eighty-seven thousand, three hundred twenty-one".