664689 has 8 divisors (see below), whose sum is σ = 892800. Its totient is φ = 439856.

The previous prime is 664687. The next prime is 664691. The reversal of 664689 is 986466.

It is an interprime number because it is at equal distance from previous prime (664687) and next prime (664691).

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

It is a cyclic number.

It is not a de Polignac number, because 664689 - 2¹ = 664687 is a prime.

It is a super-2 number, since 2×664689² = 883622933442, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (664687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 297 + ... + 1190.

It is an arithmetic number, because the mean of its divisors is an integer number (111600).

2⁶⁶⁴⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

664689 is a deficient number, since it is larger than the sum of its proper divisors (228111).

664689 is a wasteful number, since it uses less digits than its factorization.

664689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639.

The product of its digits is 62208, while the sum is 39.

The square root of 664689 is about 815.2846128807. The cubic root of 664689 is about 87.2715783663.

The spelling of 664689 in words is "six hundred sixty-four thousand, six hundred eighty-nine".