666109109 has 4 divisors (see below), whose sum is σ = 676051104. Its totient is φ = 656167116.

The previous prime is 666109099. The next prime is 666109151. The reversal of 666109109 is 901901666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 901901666 = 2 ⋅450950833.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666109109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666109009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4970897 + ... + 4971030.

It is an arithmetic number, because the mean of its divisors is an integer number (169012776).

Almost surely, 2^666109109 is an apocalyptic number.

It is an amenable number.

666109109 is a deficient number, since it is larger than the sum of its proper divisors (9941995).

666109109 is an equidigital number, since it uses as much as digits as its factorization.

666109109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9941994.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 666109109 is about 25809.0896584905. The cubic root of 666109109 is about 873.3368610693.

The spelling of 666109109 in words is "six hundred sixty-six million, one hundred nine thousand, one hundred nine".