666791817791 has 32 divisors (see below), whose sum is σ = 746068257792. Its totient is φ = 590740802560.

The previous prime is 666791817733. The next prime is 666791817793. The reversal of 666791817791 is 197718197666.

It is a cyclic number.

It is not a de Polignac number, because 666791817791 - 2¹⁰ = 666791816767 is a prime.

It is a super-2 number, since 2×666791817791² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666791817793) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 153742775 + ... + 153747111.

It is an arithmetic number, because the mean of its divisors is an integer number (23314633056).

Almost surely, 2^666791817791 is an apocalyptic number.

666791817791 is a deficient number, since it is larger than the sum of its proper divisors (79276440001).

666791817791 is a wasteful number, since it uses less digits than its factorization.

666791817791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5599.

The product of its digits is 48009024, while the sum is 68.

The spelling of 666791817791 in words is "six hundred sixty-six billion, seven hundred ninety-one million, eight hundred seventeen thousand, seven hundred ninety-one".