3998809 has 2 divisors, whose sum is σ = 3998810. Its totient is φ = 3998808.

The previous prime is 3998801. The next prime is 3998821. The reversal of 3998809 is 9088993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2890000 + 1108809 = 1700^2 + 1053^2 .

It is an emirp because it is prime and its reverse (9088993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3998809 - 2³ = 3998801 is a prime.

It is not a weakly prime, because it can be changed into another prime (3998801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1999404 + 1999405.

It is an arithmetic number, because the mean of its divisors is an integer number (1999405).

Almost surely, 2^3998809 is an apocalyptic number.

It is an amenable number.

3998809 is a deficient number, since it is larger than the sum of its proper divisors (1).

3998809 is an equidigital number, since it uses as much as digits as its factorization.

3998809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 3998809 is about 1999.7022278329. The cubic root of 3998809 is about 158.7243486774.

The spelling of 3998809 in words is "three million, nine hundred ninety-eight thousand, eight hundred nine".