998396921 has 2 divisors, whose sum is σ = 998396922. Its totient is φ = 998396920.

The previous prime is 998396909. The next prime is 998396939. The reversal of 998396921 is 129693899.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 770839696 + 227557225 = 27764^2 + 15085^2 .

It is an emirp because it is prime and its reverse (129693899) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 998396921 - 2¹⁰ = 998395897 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (998396951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499198460 + 499198461.

It is an arithmetic number, because the mean of its divisors is an integer number (499198461).

Almost surely, 2^998396921 is an apocalyptic number.

It is an amenable number.

998396921 is a deficient number, since it is larger than the sum of its proper divisors (1).

998396921 is an equidigital number, since it uses as much as digits as its factorization.

998396921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1889568, while the sum is 56.

The square root of 998396921 is about 31597.4195307148. The cubic root of 998396921 is about 999.4653545385.

The spelling of 998396921 in words is "nine hundred ninety-eight million, three hundred ninety-six thousand, nine hundred twenty-one".