7991748581 has 2 divisors, whose sum is σ = 7991748582. Its totient is φ = 7991748580.

The previous prime is 7991748539. The next prime is 7991748587. The reversal of 7991748581 is 1858471997.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7834020100 + 157728481 = 88510^2 + 12559^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7991748581 is a prime.

It is a super-2 number, since 2×7991748581² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 7991748581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7991748587) 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 as a sum of consecutive naturals, namely, 3995874290 + 3995874291.

It is an arithmetic number, because the mean of its divisors is an integer number (3995874291).

Almost surely, 2^7991748581 is an apocalyptic number.

It is an amenable number.

7991748581 is a deficient number, since it is larger than the sum of its proper divisors (1).

7991748581 is an equidigital number, since it uses as much as digits as its factorization.

7991748581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5080320, while the sum is 59.

The square root of 7991748581 is about 89396.5803652466. The cubic root of 7991748581 is about 1999.3121452050.

The spelling of 7991748581 in words is "seven billion, nine hundred ninety-one million, seven hundred forty-eight thousand, five hundred eighty-one".