666368640 has 384 divisors, whose sum is σ = 2748859200. Its totient is φ = 152119296.

The previous prime is 666368611. The next prime is 666368657. The reversal of 666368640 is 46863666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

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, 846327 + ... + 847113.

Almost surely, 2^666368640 is an apocalyptic number.

666368640 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 666368640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1374429600).

666368640 is an abundant number, since it is smaller than the sum of its proper divisors (2082490560).

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

666368640 is a wasteful number, since it uses less digits than its factorization.

666368640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 829 (or 804 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 45.

The square root of 666368640 is about 25814.1170679921. The cubic root of 666368640 is about 873.4502701967.

The spelling of 666368640 in words is "six hundred sixty-six million, three hundred sixty-eight thousand, six hundred forty".