1998556559 has 2 divisors, whose sum is σ = 1998556560. Its totient is φ = 1998556558.

The previous prime is 1998556543. The next prime is 1998556579. The reversal of 1998556559 is 9556558991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1998556559 - 2⁴ = 1998556543 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998556579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999278279 + 999278280.

It is an arithmetic number, because the mean of its divisors is an integer number (999278280).

Almost surely, 2^1998556559 is an apocalyptic number.

1998556559 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998556559 is an equidigital number, since it uses as much as digits as its factorization.

1998556559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21870000, while the sum is 62.

The square root of 1998556559 is about 44705.2184761466. The cubic root of 1998556559 is about 1259.6178733302.

The spelling of 1998556559 in words is "one billion, nine hundred ninety-eight million, five hundred fifty-six thousand, five hundred fifty-nine".