991939159 has 2 divisors, whose sum is σ = 991939160. Its totient is φ = 991939158.

The previous prime is 991939141. The next prime is 991939163. The reversal of 991939159 is 951939199.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 991939159 - 2¹⁷ = 991808087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991939129) 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, 495969579 + 495969580.

It is an arithmetic number, because the mean of its divisors is an integer number (495969580).

Almost surely, 2^991939159 is an apocalyptic number.

991939159 is a deficient number, since it is larger than the sum of its proper divisors (1).

991939159 is an equidigital number, since it uses as much as digits as its factorization.

991939159 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 885735, while the sum is 55.

The square root of 991939159 is about 31495.0656293966. The cubic root of 991939159 is about 997.3058008095.

The spelling of 991939159 in words is "nine hundred ninety-one million, nine hundred thirty-nine thousand, one hundred fifty-nine".