1668891 has 12 divisors (see below), whose sum is σ = 2588712. Its totient is φ = 953568.

The previous prime is 1668889. The next prime is 1668911. The reversal of 1668891 is 1988661.

It is not a de Polignac number, because 1668891 - 2¹ = 1668889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1668791) 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, 5530 + ... + 5823.

It is an arithmetic number, because the mean of its divisors is an integer number (215726).

2^1668891 is an apocalyptic number.

1668891 is a deficient number, since it is larger than the sum of its proper divisors (919821).

1668891 is a wasteful number, since it uses less digits than its factorization.

1668891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11370 (or 11363 counting only the distinct ones).

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

The square root of 1668891 is about 1291.8556420901. The cubic root of 1668891 is about 118.6158314783.

The spelling of 1668891 in words is "one million, six hundred sixty-eight thousand, eight hundred ninety-one".