998841821 has 2 divisors, whose sum is σ = 998841822. Its totient is φ = 998841820.

The previous prime is 998841737. The next prime is 998841827. The reversal of 998841821 is 128148899.

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., 513520921 + 485320900 = 22661^2 + 22030^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-998841821 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 998841821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998841827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499420910 + 499420911.

It is an arithmetic number, because the mean of its divisors is an integer number (499420911).

Almost surely, 2^998841821 is an apocalyptic number.

It is an amenable number.

998841821 is a deficient number, since it is larger than the sum of its proper divisors (1).

998841821 is an equidigital number, since it uses as much as digits as its factorization.

998841821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 331776, while the sum is 50.

The square root of 998841821 is about 31604.4588784557. The cubic root of 998841821 is about 999.6137911953.

The spelling of 998841821 in words is "nine hundred ninety-eight million, eight hundred forty-one thousand, eight hundred twenty-one".