6991581615 has 16 divisors (see below), whose sum is σ = 11260617216. Its totient is φ = 3704148000.

The previous prime is 6991581547. The next prime is 6991581637. The reversal of 6991581615 is 5161851996.

It is not a de Polignac number, because 6991581615 - 2¹² = 6991577519 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1541131 + ... + 1545660.

It is an arithmetic number, because the mean of its divisors is an integer number (703788576).

Almost surely, 2^6991581615 is an apocalyptic number.

6991581615 is a deficient number, since it is larger than the sum of its proper divisors (4269035601).

6991581615 is a wasteful number, since it uses less digits than its factorization.

6991581615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3086950.

The product of its digits is 583200, while the sum is 51.

The square root of 6991581615 is about 83615.6780454479. The cubic root of 6991581615 is about 1912.1640279578.

The spelling of 6991581615 in words is "six billion, nine hundred ninety-one million, five hundred eighty-one thousand, six hundred fifteen".