6691511391 has 4 divisors (see below), whose sum is σ = 8922015192. Its totient is φ = 4461007592.

The previous prime is 6691511363. The next prime is 6691511399. The reversal of 6691511391 is 1931151966.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6691511391 - 2¹¹ = 6691509343 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6691511399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1115251896 + ... + 1115251901.

It is an arithmetic number, because the mean of its divisors is an integer number (2230503798).

Almost surely, 2^6691511391 is an apocalyptic number.

6691511391 is a deficient number, since it is larger than the sum of its proper divisors (2230503801).

6691511391 is a wasteful number, since it uses less digits than its factorization.

6691511391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2230503800.

The product of its digits is 43740, while the sum is 42.

The square root of 6691511391 is about 81801.6588523729. The cubic root of 6691511391 is about 1884.4071375117.

The spelling of 6691511391 in words is "six billion, six hundred ninety-one million, five hundred eleven thousand, three hundred ninety-one".