998634821 has 2 divisors, whose sum is σ = 998634822. Its totient is φ = 998634820.

The previous prime is 998634811. The next prime is 998634823. The reversal of 998634821 is 128436899.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 894309025 + 104325796 = 29905^2 + 10214^2 .

It is a cyclic number.

It is not a de Polignac number, because 998634821 - 2²⁶ = 931525957 is a prime.

Together with 998634823, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 998634821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998634823) 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, 499317410 + 499317411.

It is an arithmetic number, because the mean of its divisors is an integer number (499317411).

Almost surely, 2^998634821 is an apocalyptic number.

It is an amenable number.

998634821 is a deficient number, since it is larger than the sum of its proper divisors (1).

998634821 is an equidigital number, since it uses as much as digits as its factorization.

998634821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 746496, while the sum is 50.

The square root of 998634821 is about 31601.1838544065. The cubic root of 998634821 is about 999.5447330968.

The spelling of 998634821 in words is "nine hundred ninety-eight million, six hundred thirty-four thousand, eight hundred twenty-one".