7991591 has 2 divisors, whose sum is σ = 7991592. Its totient is φ = 7991590.

The previous prime is 7991579. The next prime is 7991623. The reversal of 7991591 is 1951997.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1951997) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7991591 is a prime.

It is a super-2 number, since 2×7991591² = 127731053422562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7991531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3995795 + 3995796.

It is an arithmetic number, because the mean of its divisors is an integer number (3995796).

Almost surely, 2^7991591 is an apocalyptic number.

7991591 is a deficient number, since it is larger than the sum of its proper divisors (1).

7991591 is an equidigital number, since it uses as much as digits as its factorization.

7991591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25515, while the sum is 41.

The square root of 7991591 is about 2826.9402186817. The cubic root of 7991591 is about 199.9299004331.

The spelling of 7991591 in words is "seven million, nine hundred ninety-one thousand, five hundred ninety-one".