9991559 has 2 divisors, whose sum is σ = 9991560. Its totient is φ = 9991558.

The previous prime is 9991543. The next prime is 9991567. The reversal of 9991559 is 9551999.

9991559 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 9991559 - 2⁴ = 9991543 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 (9991159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995779 + 4995780.

It is an arithmetic number, because the mean of its divisors is an integer number (4995780).

Almost surely, 2^9991559 is an apocalyptic number.

9991559 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991559 is an equidigital number, since it uses as much as digits as its factorization.

9991559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 164025, while the sum is 47.

The square root of 9991559 is about 3160.9427391207. The cubic root of 9991559 is about 215.3828333284.

It can be divided in two parts, 99915 and 59, that multiplied together give a palindrome (5894985).

The spelling of 9991559 in words is "nine million, nine hundred ninety-one thousand, five hundred fifty-nine".