7991791 has 4 divisors (see below), whose sum is σ = 8267400. Its totient is φ = 7716184.

The previous prime is 7991779. The next prime is 7991803. The reversal of 7991791 is 1971997.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (7991779) and next prime (7991803).

It is a cyclic number.

It is not a de Polignac number, because 7991791 - 2⁵ = 7991759 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 (7991701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 137761 + ... + 137818.

It is an arithmetic number, because the mean of its divisors is an integer number (2066850).

Almost surely, 2^7991791 is an apocalyptic number.

7991791 is a deficient number, since it is larger than the sum of its proper divisors (275609).

7991791 is a wasteful number, since it uses less digits than its factorization.

7991791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275608.

The product of its digits is 35721, while the sum is 43.

The square root of 7991791 is about 2826.9755923955. The cubic root of 7991791 is about 199.9315682548.

It can be divided in two parts, 79917 and 91, that added together give a palindrome (80008).

The spelling of 7991791 in words is "seven million, nine hundred ninety-one thousand, seven hundred ninety-one".