664690 has 16 divisors (see below), whose sum is σ = 1288728. Its totient is φ = 245376.

The previous prime is 664687. The next prime is 664691. The reversal of 664690 is 96466.

It can be written as a sum of positive squares in 4 ways, for example, as 192721 + 471969 = 439^2 + 687^2 .

It is a super-2 number, since 2×664690² = 883625592200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (664691) 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, 2427 + ... + 2686.

2⁶⁶⁴⁶⁹⁰ is an apocalyptic number.

664690 is a deficient number, since it is larger than the sum of its proper divisors (624038).

664690 is a wasteful number, since it uses less digits than its factorization.

664690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5133.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 664690 is about 815.2852261632. The cubic root of 664690 is about 87.2716221319.

The spelling of 664690 in words is "six hundred sixty-four thousand, six hundred ninety".