6691555791 has 12 divisors (see below), whose sum is σ = 9668227920. Its totient is φ = 4459815360.

The previous prime is 6691555751. The next prime is 6691555817. The reversal of 6691555791 is 1975551966.

6691555791 is a `hidden beast` number, since 6 + 69 + 1 + 5 + 5 + 579 + 1 = 666.

It is not a de Polignac number, because 6691555791 - 2¹⁵ = 6691523023 is a prime.

It is a super-3 number, since 3×6691555791³ (a number of 30 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6691555711) 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, 66490 + ... + 133431.

It is an arithmetic number, because the mean of its divisors is an integer number (805685660).

Almost surely, 2^6691555791 is an apocalyptic number.

6691555791 is a deficient number, since it is larger than the sum of its proper divisors (2976672129).

6691555791 is a wasteful number, since it uses less digits than its factorization.

6691555791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203646 (or 203643 counting only the distinct ones).

The product of its digits is 2551500, while the sum is 54.

The square root of 6691555791 is about 81801.9302400622. The cubic root of 6691555791 is about 1884.4113053540.

The spelling of 6691555791 in words is "six billion, six hundred ninety-one million, five hundred fifty-five thousand, seven hundred ninety-one".