991150591 has 2 divisors, whose sum is σ = 991150592. Its totient is φ = 991150590.

The previous prime is 991150583. The next prime is 991150619. The reversal of 991150591 is 195051199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991150591 - 2³ = 991150583 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991150091) 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, 495575295 + 495575296.

It is an arithmetic number, because the mean of its divisors is an integer number (495575296).

Almost surely, 2^991150591 is an apocalyptic number.

991150591 is a deficient number, since it is larger than the sum of its proper divisors (1).

991150591 is an equidigital number, since it uses as much as digits as its factorization.

991150591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18225, while the sum is 40.

The square root of 991150591 is about 31482.5442269204. The cubic root of 991150591 is about 997.0414526295.

The spelling of 991150591 in words is "nine hundred ninety-one million, one hundred fifty thousand, five hundred ninety-one".