664020 has 144 divisors (see below), whose sum is σ = 2515968. Its totient is φ = 138240.

The previous prime is 664019. The next prime is 664043. The reversal of 664020 is 20466.

664020 is a `hidden beast` number, since 6 + 640 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 663984 and 664002.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 664020.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 21405 + ... + 21435.

It is an arithmetic number, because the mean of its divisors is an integer number (17472).

2⁶⁶⁴⁰²⁰ is an apocalyptic number.

664020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 664020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1257984).

664020 is an abundant number, since it is smaller than the sum of its proper divisors (1851948).

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

664020 is a wasteful number, since it uses less digits than its factorization.

664020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 664020 is about 814.8742234235. The cubic root of 664020 is about 87.2422893381.

Adding to 664020 its reverse (20466), we get a palindrome (684486).

The spelling of 664020 in words is "six hundred sixty-four thousand, twenty".