3981209 has 2 divisors, whose sum is σ = 3981210. Its totient is φ = 3981208.

The previous prime is 3981193. The next prime is 3981217. The reversal of 3981209 is 9021893.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3433609 + 547600 = 1853^2 + 740^2 .

It is an emirp because it is prime and its reverse (9021893) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3981209 - 2⁴ = 3981193 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 (3981709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1990604 + 1990605.

It is an arithmetic number, because the mean of its divisors is an integer number (1990605).

Almost surely, 2^3981209 is an apocalyptic number.

It is an amenable number.

3981209 is a deficient number, since it is larger than the sum of its proper divisors (1).

3981209 is an equidigital number, since it uses as much as digits as its factorization.

3981209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 3981209 is about 1995.2967197888. The cubic root of 3981209 is about 158.4911411555.

The spelling of 3981209 in words is "three million, nine hundred eighty-one thousand, two hundred nine".