998128809 has 12 divisors (see below), whose sum is σ = 1442152452. Its totient is φ = 665229600.

The previous prime is 998128753. The next prime is 998128823. The reversal of 998128809 is 908821899.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 591219225 + 406909584 = 24315^2 + 20172^2 .

It is not a de Polignac number, because 998128809 - 2²¹ = 996031657 is a prime.

It is a super-2 number, since 2×998128809² = 1992522238711516962, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (998128889) 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 in 11 ways as a sum of consecutive naturals, for example, 22399 + ... + 49979.

It is an arithmetic number, because the mean of its divisors is an integer number (120179371).

Almost surely, 2^998128809 is an apocalyptic number.

It is an amenable number.

998128809 is a deficient number, since it is larger than the sum of its proper divisors (444023643).

998128809 is a wasteful number, since it uses less digits than its factorization.

998128809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31608 (or 31605 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 54.

The square root of 998128809 is about 31593.1766209098. The cubic root of 998128809 is about 999.3758802222.

The spelling of 998128809 in words is "nine hundred ninety-eight million, one hundred twenty-eight thousand, eight hundred nine".