209409841 has 9 divisors (see below), whose sum is σ = 217315371. Its totient is φ = 201783624.

The previous prime is 209409839. The next prime is 209409847. The reversal of 209409841 is 148904902.

It is a happy number.

The square root of 209409841 is 14471.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 109809441 + 99600400 = 10479^2 + 9980^2 .

It is not a de Polignac number, because 209409841 - 2¹ = 209409839 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 209409841.

It is not an unprimeable number, because it can be changed into a prime (209409847) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 419410 + ... + 419908.

Almost surely, 2^209409841 is an apocalyptic number.

209409841 is the 14471-st square number.

209409841 is the 7236-th centered octagonal number.

It is an amenable number.

209409841 is a deficient number, since it is larger than the sum of its proper divisors (7905530).

209409841 is an frugal number, since it uses more digits than its factorization.

209409841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056 (or 528 counting only the distinct ones).

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

The cubic root of 209409841 is about 593.8348698479.

Multiplying 209409841 by its product of nonzero digits (20736), we get a square (4342322462976 = 2083824²).

The spelling of 209409841 in words is "two hundred nine million, four hundred nine thousand, eight hundred forty-one".