666107721699 has 32 divisors (see below), whose sum is σ = 1037279748096. Its totient is φ = 372296411040.

The previous prime is 666107721637. The next prime is 666107721701. The reversal of 666107721699 is 996127701666.

It is not a de Polignac number, because 666107721699 - 2²⁷ = 665973503971 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666107721619) 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 31 ways as a sum of consecutive naturals, for example, 1335784 + ... + 1765370.

It is an arithmetic number, because the mean of its divisors is an integer number (32414992128).

Almost surely, 2^666107721699 is an apocalyptic number.

666107721699 is a deficient number, since it is larger than the sum of its proper divisors (371172026397).

666107721699 is a wasteful number, since it uses less digits than its factorization.

666107721699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431215.

The product of its (nonzero) digits is 10287648, while the sum is 60.

The spelling of 666107721699 in words is "six hundred sixty-six billion, one hundred seven million, seven hundred twenty-one thousand, six hundred ninety-nine".