666540219647 has 16 divisors (see below), whose sum is σ = 699681840000. Its totient is φ = 634216946688.

The previous prime is 666540219641. The next prime is 666540219661. The reversal of 666540219647 is 746912045666.

It is a cyclic number.

It is not a de Polignac number, because 666540219647 - 2²² = 666536025343 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 666540219592 and 666540219601.

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 pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2018573 + ... + 2325449.

It is an arithmetic number, because the mean of its divisors is an integer number (43730115000).

Almost surely, 2^666540219647 is an apocalyptic number.

666540219647 is a deficient number, since it is larger than the sum of its proper divisors (33141620353).

666540219647 is a wasteful number, since it uses less digits than its factorization.

666540219647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308210.

The product of its (nonzero) digits is 13063680, while the sum is 56.

The spelling of 666540219647 in words is "six hundred sixty-six billion, five hundred forty million, two hundred nineteen thousand, six hundred forty-seven".