666240 has 64 divisors (see below), whose sum is σ = 2129760. Its totient is φ = 177152.

The previous prime is 666233. The next prime is 666269. The reversal of 666240 is 42666.

It is a tau number, because it is divible by the number of its divisors (64).

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 666240.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1747 + ... + 2093.

2⁶⁶⁶²⁴⁰ is an apocalyptic number.

666240 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 666240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1064880).

666240 is an abundant number, since it is smaller than the sum of its proper divisors (1463520).

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

666240 is a wasteful number, since it uses less digits than its factorization.

666240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369 (or 357 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 666240 is about 816.2352602038. The cubic root of 666240 is about 87.3394061132.

The spelling of 666240 in words is "six hundred sixty-six thousand, two hundred forty".