666791817794 has 16 divisors (see below), whose sum is σ = 1007881388856. Its totient is φ = 330836937600.

The previous prime is 666791817793. The next prime is 666791817799. The reversal of 666791817794 is 497718197666.

It can be written as a sum of positive squares in 4 ways, for example, as 504675264025 + 162116553769 = 710405^2 + 402637^2 .

It is a super-2 number, since 2×666791817794² (a number of 24 digits) contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 1156277 + ... + 1634184.

Almost surely, 2^666791817794 is an apocalyptic number.

666791817794 is a deficient number, since it is larger than the sum of its proper divisors (341089571062).

666791817794 is a wasteful number, since it uses less digits than its factorization.

666791817794 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2791381.

The product of its digits is 192036096, while the sum is 71.

The spelling of 666791817794 in words is "six hundred sixty-six billion, seven hundred ninety-one million, eight hundred seventeen thousand, seven hundred ninety-four".