666540219648 has 576 divisors, whose sum is σ = 2002991800320. Its totient is φ = 195880550400.

The previous prime is 666540219641. The next prime is 666540219661. The reversal of 666540219648 is 846912045666.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666540219641) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1539353640 + ... + 1539354072.

It is an arithmetic number, because the mean of its divisors is an integer number (3477416320).

Almost surely, 2^666540219648 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 666540219648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1001495900160).

666540219648 is an abundant number, since it is smaller than the sum of its proper divisors (1336451580672).

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

666540219648 is a wasteful number, since it uses less digits than its factorization.

666540219648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 626 (or 612 counting only the distinct ones).

The product of its (nonzero) digits is 14929920, while the sum is 57.

The spelling of 666540219648 in words is "six hundred sixty-six billion, five hundred forty million, two hundred nineteen thousand, six hundred forty-eight".