998979809 has 2 divisors, whose sum is σ = 998979810. Its totient is φ = 998979808.

The previous prime is 998979803. The next prime is 998979829. The reversal of 998979809 is 908979899.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 843728209 + 155251600 = 29047^2 + 12460^2 .

It is an emirp because it is prime and its reverse (908979899) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-998979809 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (998979803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499489904 + 499489905.

It is an arithmetic number, because the mean of its divisors is an integer number (499489905).

Almost surely, 2^998979809 is an apocalyptic number.

It is an amenable number.

998979809 is a deficient number, since it is larger than the sum of its proper divisors (1).

998979809 is an equidigital number, since it uses as much as digits as its factorization.

998979809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26453952, while the sum is 68.

The square root of 998979809 is about 31606.6418494594. The cubic root of 998979809 is about 999.6598206244.

It can be divided in two parts, 9989 and 79809, that added together give a palindrome (89798).

The spelling of 998979809 in words is "nine hundred ninety-eight million, nine hundred seventy-nine thousand, eight hundred nine".