99991559 has 2 divisors, whose sum is σ = 99991560. Its totient is φ = 99991558.

The previous prime is 99991519. The next prime is 99991561. The reversal of 99991559 is 95519999.

It is a strong prime.

It is an emirp because it is prime and its reverse (95519999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99991559 - 2⁸ = 99991303 is a prime.

Together with 99991561, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99991519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49995779 + 49995780.

It is an arithmetic number, because the mean of its divisors is an integer number (49995780).

Almost surely, 2^99991559 is an apocalyptic number.

99991559 is a deficient number, since it is larger than the sum of its proper divisors (1).

99991559 is an equidigital number, since it uses as much as digits as its factorization.

99991559 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1476225, while the sum is 56.

The square root of 99991559 is about 9999.5779410933. The cubic root of 99991559 is about 464.1458231100.

The spelling of 99991559 in words is "ninety-nine million, nine hundred ninety-one thousand, five hundred fifty-nine".