1668643 has 4 divisors (see below), whose sum is σ = 1672000. Its totient is φ = 1665288.

The previous prime is 1668629. The next prime is 1668647. The reversal of 1668643 is 3468661.

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

It is a cyclic number.

It is not a de Polignac number, because 1668643 - 2⁹ = 1668131 is a prime.

It is a super-2 number, since 2×1668643² = 5568738922898, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 6.

It is a junction number, because it is equal to n+sod(n) for n = 1668599 and 1668608.

It is not an unprimeable number, because it can be changed into a prime (1668647) 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, 768 + ... + 1981.

It is an arithmetic number, because the mean of its divisors is an integer number (418000).

2^1668643 is an apocalyptic number.

1668643 is a deficient number, since it is larger than the sum of its proper divisors (3357).

1668643 is an equidigital number, since it uses as much as digits as its factorization.

1668643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3356.

The product of its digits is 20736, while the sum is 34.

The square root of 1668643 is about 1291.7596525670. The cubic root of 1668643 is about 118.6099556834.

The spelling of 1668643 in words is "one million, six hundred sixty-eight thousand, six hundred forty-three".