6991131699981 has 160 divisors (see below), whose sum is σ = 13092040241280. Its totient is φ = 3654508492800.

The previous prime is 6991131699917. The next prime is 6991131699983. The reversal of 6991131699981 is 1899961311996.

6991131699981 is a `hidden beast` number, since 69 + 91 + 1 + 316 + 9 + 99 + 81 = 666.

It is not a de Polignac number, because 6991131699981 - 2⁶ = 6991131699917 is a prime.

It is a super-2 number, since 2×6991131699981² (a number of 26 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991131699983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 15848041 + ... + 16283201.

It is an arithmetic number, because the mean of its divisors is an integer number (81825251508).

Almost surely, 2^{6991131699981} is an apocalyptic number.

It is an amenable number.

6991131699981 is a deficient number, since it is larger than the sum of its proper divisors (6100908541299).

6991131699981 is a wasteful number, since it uses less digits than its factorization.

6991131699981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435289 (or 435280 counting only the distinct ones).

The product of its digits is 51018336, while the sum is 72.

The spelling of 6991131699981 in words is "six trillion, nine hundred ninety-one billion, one hundred thirty-one million, six hundred ninety-nine thousand, nine hundred eighty-one".