991840511 has 2 divisors, whose sum is σ = 991840512. Its totient is φ = 991840510.

The previous prime is 991840439. The next prime is 991840529. The reversal of 991840511 is 115048199.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991840511 is a prime.

It is a super-2 number, since 2×991840511² = 1967495198521482242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991840111) 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, 495920255 + 495920256.

It is an arithmetic number, because the mean of its divisors is an integer number (495920256).

Almost surely, 2^991840511 is an apocalyptic number.

991840511 is a deficient number, since it is larger than the sum of its proper divisors (1).

991840511 is an equidigital number, since it uses as much as digits as its factorization.

991840511 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 38.

The square root of 991840511 is about 31493.4995038659. The cubic root of 991840511 is about 997.2727391433.

The spelling of 991840511 in words is "nine hundred ninety-one million, eight hundred forty thousand, five hundred eleven".