209438609 has 4 divisors (see below), whose sum is σ = 216660660. Its totient is φ = 202216560.

The previous prime is 209438597. The next prime is 209438639. The reversal of 209438609 is 906834902.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906834902 = 2 ⋅453417451.

It can be written as a sum of positive squares in 2 ways, for example, as 43930384 + 165508225 = 6628^2 + 12865^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209438609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209438639) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3610982 + ... + 3611039.

It is an arithmetic number, because the mean of its divisors is an integer number (54165165).

Almost surely, 2^209438609 is an apocalyptic number.

209438609 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

209438609 is a deficient number, since it is larger than the sum of its proper divisors (7222051).

209438609 is an equidigital number, since it uses as much as digits as its factorization.

209438609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7222050.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 209438609 is about 14471.9939538406. The cubic root of 209438609 is about 593.8620615966.

The spelling of 209438609 in words is "two hundred nine million, four hundred thirty-eight thousand, six hundred nine".