666840240 has 240 divisors, whose sum is σ = 2459976480. Its totient is φ = 160542720.

The previous prime is 666840199. The next prime is 666840241. The reversal of 666840240 is 42048666.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (240).

It is a hoax number, since the sum of its digits (36) 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 (36).

It is a junction number, because it is equal to n+sod(n) for n = 666840195 and 666840204.

It is not an unprimeable number, because it can be changed into a prime (666840241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2130324 + ... + 2130636.

It is an arithmetic number, because the mean of its divisors is an integer number (10249902).

Almost surely, 2^666840240 is an apocalyptic number.

666840240 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

666840240 is the 12912-nd decagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666840240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1229988240).

666840240 is an abundant number, since it is smaller than the sum of its proper divisors (1793136240).

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

666840240 is a wasteful number, since it uses less digits than its factorization.

666840240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612 (or 603 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 666840240 is about 25823.2499891087. The cubic root of 666840240 is about 873.6562732941.

The spelling of 666840240 in words is "six hundred sixty-six million, eight hundred forty thousand, two hundred forty".