991159549 has 2 divisors, whose sum is σ = 991159550. Its totient is φ = 991159548.

The previous prime is 991159541. The next prime is 991159573. The reversal of 991159549 is 945951199.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 944332900 + 46826649 = 30730^2 + 6843^2 .

It is a cyclic number.

It is not a de Polignac number, because 991159549 - 2³ = 991159541 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991159496 and 991159505.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991159541) 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, 495579774 + 495579775.

It is an arithmetic number, because the mean of its divisors is an integer number (495579775).

Almost surely, 2^991159549 is an apocalyptic number.

It is an amenable number.

991159549 is a deficient number, since it is larger than the sum of its proper divisors (1).

991159549 is an equidigital number, since it uses as much as digits as its factorization.

991159549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 656100, while the sum is 52.

The square root of 991159549 is about 31482.6864959139. The cubic root of 991159549 is about 997.0444563676.

The spelling of 991159549 in words is "nine hundred ninety-one million, one hundred fifty-nine thousand, five hundred forty-nine".