6660107991 has 12 divisors (see below), whose sum is σ = 9626410768. Its totient is φ = 4437185184.

The previous prime is 6660107959. The next prime is 6660108001. The reversal of 6660107991 is 1997010666.

It is not a de Polignac number, because 6660107991 - 2⁵ = 6660107959 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 (6660107291) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225910 + ... + 253683.

Almost surely, 2^6660107991 is an apocalyptic number.

6660107991 is a deficient number, since it is larger than the sum of its proper divisors (2966302777).

6660107991 is a wasteful number, since it uses less digits than its factorization.

6660107991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481142 (or 481139 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 45.

The square root of 6660107991 is about 81609.4846877494. The cubic root of 6660107991 is about 1881.4546602419.

The spelling of 6660107991 in words is "six billion, six hundred sixty million, one hundred seven thousand, nine hundred ninety-one".