1668409 has 4 divisors (see below), whose sum is σ = 1756240. Its totient is φ = 1580580.

The previous prime is 1668379. The next prime is 1668427. The reversal of 1668409 is 9048661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1668409 - 2¹¹ = 1666361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1668449) 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, 43887 + ... + 43924.

It is an arithmetic number, because the mean of its divisors is an integer number (439060).

2^1668409 is an apocalyptic number.

1668409 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1668409 is a deficient number, since it is larger than the sum of its proper divisors (87831).

1668409 is an equidigital number, since it uses as much as digits as its factorization.

1668409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87830.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 1668409 is about 1291.6690752666. The cubic root of 1668409 is about 118.6044110528.

The spelling of 1668409 in words is "one million, six hundred sixty-eight thousand, four hundred nine".