19686681 has 18 divisors (see below), whose sum is σ = 33079722. Its totient is φ = 11249280.

The previous prime is 19686673. The next prime is 19686727. The reversal of 19686681 is 18668691.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18352656 + 1334025 = 4284^2 + 1155^2 .

It is not a de Polignac number, because 19686681 - 2³ = 19686673 is a prime.

It is a super-2 number, since 2×19686681² = 775130817591522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (19686481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 21880 + ... + 22761.

Almost surely, 2^19686681 is an apocalyptic number.

It is an amenable number.

19686681 is a deficient number, since it is larger than the sum of its proper divisors (13393041).

19686681 is a wasteful number, since it uses less digits than its factorization.

19686681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44661 (or 44651 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 19686681 is about 4436.9675455203. The cubic root of 19686681 is about 270.0168302266.

It can be divided in two parts, 1968 and 6681, that added together give a square (8649 = 93²).

The spelling of 19686681 in words is "nineteen million, six hundred eighty-six thousand, six hundred eighty-one".