398808821 has 2 divisors, whose sum is σ = 398808822. Its totient is φ = 398808820.

The previous prime is 398808793. The next prime is 398808863. The reversal of 398808821 is 128808893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 398800900 + 7921 = 19970^2 + 89^2 .

It is an emirp because it is prime and its reverse (128808893) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 398808821 - 2⁶ = 398808757 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (398808871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199404410 + 199404411.

It is an arithmetic number, because the mean of its divisors is an integer number (199404411).

Almost surely, 2^398808821 is an apocalyptic number.

It is an amenable number.

398808821 is a deficient number, since it is larger than the sum of its proper divisors (1).

398808821 is an equidigital number, since it uses as much as digits as its factorization.

398808821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 221184, while the sum is 47.

The square root of 398808821 is about 19970.1983214990. The cubic root of 398808821 is about 736.0741823513.

The spelling of 398808821 in words is "three hundred ninety-eight million, eight hundred eight thousand, eight hundred twenty-one".