1686981 has 12 divisors (see below), whose sum is σ = 2353568. Its totient is φ = 1074744.

The previous prime is 1686973. The next prime is 1686983. The reversal of 1686981 is 1896861.

It is not a de Polignac number, because 1686981 - 2³ = 1686973 is a prime.

It is a super-2 number, since 2×1686981² = 5691809788722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1686983) 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 11 ways as a sum of consecutive naturals, for example, 1056 + ... + 2118.

2^1686981 is an apocalyptic number.

It is an amenable number.

1686981 is a deficient number, since it is larger than the sum of its proper divisors (666587).

1686981 is a wasteful number, since it uses less digits than its factorization.

1686981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1112 (or 1089 counting only the distinct ones).

The product of its digits is 20736, while the sum is 39.

The square root of 1686981 is about 1298.8383271216. The cubic root of 1686981 is about 119.0428722958.

The spelling of 1686981 in words is "one million, six hundred eighty-six thousand, nine hundred eighty-one".