1687491931 has 4 divisors (see below), whose sum is σ = 1687582864. Its totient is φ = 1687401000.

The previous prime is 1687491929. The next prime is 1687491937. The reversal of 1687491931 is 1391947861.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a 3-Lehmer number, since φ(1687491931) divides (1687491931-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1687491931 - 2¹ = 1687491929 is a prime.

It is a super-2 number, since 2×1687491931² = 5695258034380217522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1687491937) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6495 + ... + 58456.

It is an arithmetic number, because the mean of its divisors is an integer number (421895716).

Almost surely, 2^1687491931 is an apocalyptic number.

1687491931 is the 25981-st heptagonal number.

1687491931 is a deficient number, since it is larger than the sum of its proper divisors (90933).

1687491931 is an equidigital number, since it uses as much as digits as its factorization.

1687491931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90932.

The product of its digits is 326592, while the sum is 49.

The square root of 1687491931 is about 41079.0936000297. The cubic root of 1687491931 is about 1190.5488913821.

The spelling of 1687491931 in words is "one billion, six hundred eighty-seven million, four hundred ninety-one thousand, nine hundred thirty-one".