668643 has 8 divisors (see below), whose sum is σ = 900288. Its totient is φ = 441384.

The previous prime is 668623. The next prime is 668671. The reversal of 668643 is 346866.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 668643 - 2⁵ = 668611 is a prime.

It is a super-2 number, since 2×668643² = 894166922898, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668623) 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 7 ways as a sum of consecutive naturals, for example, 721 + ... + 1362.

It is an arithmetic number, because the mean of its divisors is an integer number (112536).

2⁶⁶⁸⁶⁴³ is an apocalyptic number.

668643 is a deficient number, since it is larger than the sum of its proper divisors (231645).

668643 is a wasteful number, since it uses less digits than its factorization.

668643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2193.

The product of its digits is 20736, while the sum is 33.

The square root of 668643 is about 817.7059373638. The cubic root of 668643 is about 87.4442856206. Note that the first 3 decimals are identical.

The spelling of 668643 in words is "six hundred sixty-eight thousand, six hundred forty-three".