6991999647 has 16 divisors (see below), whose sum is σ = 9352419840. Its totient is φ = 4646476800.

The previous prime is 6991999627. The next prime is 6991999681. The reversal of 6991999647 is 7469991996.

It is not a de Polignac number, because 6991999647 - 2¹⁰ = 6991998623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991999607) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2598879 + ... + 2601567.

It is an arithmetic number, because the mean of its divisors is an integer number (584526240).

Almost surely, 2^6991999647 is an apocalyptic number.

6991999647 is a deficient number, since it is larger than the sum of its proper divisors (2360420193).

6991999647 is a wasteful number, since it uses less digits than its factorization.

6991999647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5134.

The product of its digits is 59521392, while the sum is 69.

The square root of 6991999647 is about 83618.1777306825. The cubic root of 6991999647 is about 1912.2021371137.

The spelling of 6991999647 in words is "six billion, nine hundred ninety-one million, nine hundred ninety-nine thousand, six hundred forty-seven".