999998689 has 2 divisors, whose sum is σ = 999998690.
Its totient is φ = 999998688.
The previous prime is 999998687. The next prime is 999998693. The reversal of 999998689 is 986899999.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 834747664 + 165251025 = 28892^2 + 12855^2
It is a cyclic number.
It is not a de Polignac number, because 999998689 - 21 = 999998687 is a prime.
Together with 999998687, it forms a pair of twin primes.
It is not a weakly prime, because it can be changed into another prime (999998683) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999344 + 499999345.
It is an arithmetic number, because the mean of its divisors is an integer number (499999345).
Almost surely, 2999998689 is an apocalyptic number.
It is an amenable number.
999998689 is a deficient number, since it is larger than the sum of its proper divisors (1).
999998689 is an equidigital number, since it uses as much as digits as its factorization.
999998689 is an evil number, because the sum of its binary digits is even.
The product of its digits is 204073344, while the sum is 76.
The square root of 999998689 is about 31622.7558729469.
The cubic root of 999998689 is about 999.9995629998.
Note that the first 3 decimals are identical.
The spelling of 999998689 in words is "nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred eighty-nine".