664643 has 4 divisors (see below), whose sum is σ = 759600. Its totient is φ = 569688.

The previous prime is 664633. The next prime is 664661. The reversal of 664643 is 346466.

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

It is not a de Polignac number, because 664643 - 2⁶ = 664579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47468 + ... + 47481.

It is an arithmetic number, because the mean of its divisors is an integer number (189900).

2⁶⁶⁴⁶⁴³ is an apocalyptic number.

664643 is a deficient number, since it is larger than the sum of its proper divisors (94957).

664643 is an equidigital number, since it uses as much as digits as its factorization.

664643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94956.

The product of its digits is 10368, while the sum is 29.

The square root of 664643 is about 815.2564013855. The cubic root of 664643 is about 87.2695651014.

The spelling of 664643 in words is "six hundred sixty-four thousand, six hundred forty-three".