1686861 has 18 divisors (see below), whose sum is σ = 2679950. Its totient is φ = 1021680.

The previous prime is 1686857. The next prime is 1686871.

1686861 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 1334025 + 352836 = 1155^2 + 594^2 .

It is not a de Polignac number, because 1686861 - 2² = 1686857 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1686851) 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 17 ways as a sum of consecutive naturals, for example, 315 + ... + 1863.

2^1686861 is an apocalyptic number.

1686861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1686861 is a deficient number, since it is larger than the sum of its proper divisors (993089).

1686861 is a wasteful number, since it uses less digits than its factorization.

1686861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1577 (or 1563 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 1686861 is about 1298.7921311742. The cubic root of 1686861 is about 119.0400496038.

The spelling of 1686861 in words is "one million, six hundred eighty-six thousand, eight hundred sixty-one".