664890 has 32 divisors (see below), whose sum is σ = 1641600. Its totient is φ = 172224.

The previous prime is 664879. The next prime is 664891. The reversal of 664890 is 98466.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 811 + ... + 1409.

It is an arithmetic number, because the mean of its divisors is an integer number (51300).

2⁶⁶⁴⁸⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (820800).

664890 is an abundant number, since it is smaller than the sum of its proper divisors (976710).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

664890 is a wasteful number, since it uses less digits than its factorization.

664890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646.

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 664890 is about 815.4078733983. The cubic root of 664890 is about 87.2803743694.

The spelling of 664890 in words is "six hundred sixty-four thousand, eight hundred ninety".