1687719681 has 12 divisors (see below), whose sum is σ = 2445186640. Its totient is φ = 1121745240.

The previous prime is 1687719673. The next prime is 1687719731. The reversal of 1687719681 is 1869177861.

It is not a de Polignac number, because 1687719681 - 2³ = 1687719673 is a prime.

It is a super-2 number, since 2×1687719681² = 5696795443269483522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1687719611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 280291 + ... + 286248.

Almost surely, 2^1687719681 is an apocalyptic number.

It is an amenable number.

1687719681 is a deficient number, since it is larger than the sum of its proper divisors (757466959).

1687719681 is a wasteful number, since it uses less digits than its factorization.

1687719681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566876 (or 566873 counting only the distinct ones).

The product of its digits is 1016064, while the sum is 54.

The square root of 1687719681 is about 41081.8655978523. The cubic root of 1687719681 is about 1190.6024492309.

The spelling of 1687719681 in words is "one billion, six hundred eighty-seven million, seven hundred nineteen thousand, six hundred eighty-one".