209904841 has 2 divisors, whose sum is σ = 209904842. Its totient is φ = 209904840.

The previous prime is 209904839. The next prime is 209904847. The reversal of 209904841 is 148409902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187142400 + 22762441 = 13680^2 + 4771^2 .

It is a cyclic number.

It is not a de Polignac number, because 209904841 - 2¹ = 209904839 is a prime.

Together with 209904839, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 209904841.

It is not a weakly prime, because it can be changed into another prime (209904847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104952420 + 104952421.

It is an arithmetic number, because the mean of its divisors is an integer number (104952421).

Almost surely, 2^209904841 is an apocalyptic number.

It is an amenable number.

209904841 is a deficient number, since it is larger than the sum of its proper divisors (1).

209904841 is an equidigital number, since it uses as much as digits as its factorization.

209904841 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 209904841 is about 14488.0930767303. The cubic root of 209904841 is about 594.3024011295.

The spelling of 209904841 in words is "two hundred nine million, nine hundred four thousand, eight hundred forty-one".