7991221871 has 4 divisors (see below), whose sum is σ = 8003573712. Its totient is φ = 7978870032.

The previous prime is 7991221829. The next prime is 7991221873. The reversal of 7991221871 is 1781221997.

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 7991221871 - 2¹⁰ = 7991220847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7991221873) 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, 6174950 + ... + 6176243.

It is an arithmetic number, because the mean of its divisors is an integer number (2000893428).

Almost surely, 2^7991221871 is an apocalyptic number.

7991221871 is a deficient number, since it is larger than the sum of its proper divisors (12351841).

7991221871 is a wasteful number, since it uses less digits than its factorization.

7991221871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12351840.

The product of its digits is 127008, while the sum is 47.

The square root of 7991221871 is about 89393.6343986528. The cubic root of 7991221871 is about 1999.2682215328.

The spelling of 7991221871 in words is "seven billion, nine hundred ninety-one million, two hundred twenty-one thousand, eight hundred seventy-one".