1668399 has 16 divisors (see below), whose sum is σ = 2334720. Its totient is φ = 1058400.

The previous prime is 1668379. The next prime is 1668427. The reversal of 1668399 is 9938661.

It is not a de Polignac number, because 1668399 - 2¹¹ = 1666351 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1668399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668319) 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 15 ways as a sum of consecutive naturals, for example, 10974 + ... + 11124.

It is an arithmetic number, because the mean of its divisors is an integer number (145920).

2^1668399 is an apocalyptic number.

1668399 is a deficient number, since it is larger than the sum of its proper divisors (666321).

1668399 is a wasteful number, since it uses less digits than its factorization.

1668399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310.

The product of its digits is 69984, while the sum is 42.

The square root of 1668399 is about 1291.6652043002. The cubic root of 1668399 is about 118.6041740912.

The spelling of 1668399 in words is "one million, six hundred sixty-eight thousand, three hundred ninety-nine".