666305640 has 576 divisors, whose sum is σ = 2976704640. Its totient is φ = 124830720.

The previous prime is 666305639. The next prime is 666305641. The reversal of 666305640 is 46503666.

It is an interprime number because it is at equal distance from previous prime (666305639) and next prime (666305641).

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 = 666305595 and 666305604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666305641) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 15495459 + ... + 15495501.

It is an arithmetic number, because the mean of its divisors is an integer number (5167890).

Almost surely, 2^666305640 is an apocalyptic number.

666305640 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 666305640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1488352320).

666305640 is an abundant number, since it is smaller than the sum of its proper divisors (2310399000).

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

666305640 is a wasteful number, since it uses less digits than its factorization.

666305640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 36.

The square root of 666305640 is about 25812.8967766115. The cubic root of 666305640 is about 873.4227433404.

The spelling of 666305640 in words is "six hundred sixty-six million, three hundred five thousand, six hundred forty".