3998221 has 2 divisors, whose sum is σ = 3998222. Its totient is φ = 3998220.

The previous prime is 3998219. The next prime is 3998233. The reversal of 3998221 is 1228993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2842596 + 1155625 = 1686^2 + 1075^2 .

It is an emirp because it is prime and its reverse (1228993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3998221 - 2¹ = 3998219 is a prime.

Together with 3998219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3998261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1999110 + 1999111.

It is an arithmetic number, because the mean of its divisors is an integer number (1999111).

Almost surely, 2^3998221 is an apocalyptic number.

It is an amenable number.

3998221 is a deficient number, since it is larger than the sum of its proper divisors (1).

3998221 is an equidigital number, since it uses as much as digits as its factorization.

3998221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 3998221 is about 1999.5552005384. Note that the first 3 decimals coincide. The cubic root of 3998221 is about 158.7165684866.

The spelling of 3998221 in words is "three million, nine hundred ninety-eight thousand, two hundred twenty-one".