7991574221 has 4 divisors (see below), whose sum is σ = 7999464252. Its totient is φ = 7983684192.

The previous prime is 7991574203. The next prime is 7991574223. The reversal of 7991574221 is 1224751997.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1224751997 = 7 ⋅174964571.

It can be written as a sum of positive squares in 2 ways, for example, as 593166025 + 7398408196 = 24355^2 + 86014^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7991574221 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7991574223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3943496 + ... + 3945521.

It is an arithmetic number, because the mean of its divisors is an integer number (1999866063).

Almost surely, 2^7991574221 is an apocalyptic number.

It is an amenable number.

7991574221 is a deficient number, since it is larger than the sum of its proper divisors (7890031).

7991574221 is a wasteful number, since it uses less digits than its factorization.

7991574221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7890030.

The product of its digits is 317520, while the sum is 47.

The square root of 7991574221 is about 89395.6051548397. The cubic root of 7991574221 is about 1999.2976050996.

The spelling of 7991574221 in words is "seven billion, nine hundred ninety-one million, five hundred seventy-four thousand, two hundred twenty-one".