1688691 has 4 divisors (see below), whose sum is σ = 2251592. Its totient is φ = 1125792.

The previous prime is 1688681. The next prime is 1688741. The reversal of 1688691 is 1968861.

1688691 is nontrivially palindromic in base 2.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1688691 - 2⁹ = 1688179 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1688651) 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 3 ways as a sum of consecutive naturals, for example, 281446 + ... + 281451.

It is an arithmetic number, because the mean of its divisors is an integer number (562898).

2^1688691 is an apocalyptic number.

1688691 is a deficient number, since it is larger than the sum of its proper divisors (562901).

1688691 is an equidigital number, since it uses as much as digits as its factorization.

1688691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562900.

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

The square root of 1688691 is about 1299.4964409339. The cubic root of 1688691 is about 119.0830811205.

The spelling of 1688691 in words is "one million, six hundred eighty-eight thousand, six hundred ninety-one".