666663194791 has 16 divisors (see below), whose sum is σ = 741208010400. Its totient is φ = 594551664000.

The previous prime is 666663194749. The next prime is 666663194801. The reversal of 666663194791 is 197491366666.

It is a cyclic number.

It is not a de Polignac number, because 666663194791 - 2²⁹ = 666126323879 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666663194711) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2631456 + ... + 2873653.

It is an arithmetic number, because the mean of its divisors is an integer number (46325500650).

Almost surely, 2^666663194791 is an apocalyptic number.

666663194791 is a deficient number, since it is larger than the sum of its proper divisors (74544815609).

666663194791 is a wasteful number, since it uses less digits than its factorization.

666663194791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5505330.

The product of its digits is 52907904, while the sum is 64.

Multiplying 666663194791 by its sum of digits (64), we get a palindrome (42666444466624).

The spelling of 666663194791 in words is "six hundred sixty-six billion, six hundred sixty-three million, one hundred ninety-four thousand, seven hundred ninety-one".