666520 has 32 divisors (see below), whose sum is σ = 1580400. Its totient is φ = 252288.

The previous prime is 666511. The next prime is 666527. The reversal of 666520 is 25666.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666527) by changing a digit.

666520 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 322 + ... + 1198.

2⁶⁶⁶⁵²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (790200).

666520 is an abundant number, since it is smaller than the sum of its proper divisors (913880).

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

666520 is a wasteful number, since it uses less digits than its factorization.

666520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 907 (or 903 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 666520 is about 816.4067613635. The cubic root of 666520 is about 87.3516397470.

The spelling of 666520 in words is "six hundred sixty-six thousand, five hundred twenty".