209813 has 2 divisors, whose sum is σ = 209814. Its totient is φ = 209812.

The previous prime is 209809. The next prime is 209819. The reversal of 209813 is 318902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 209764 + 49 = 458^2 + 7^2 .

It is a cyclic number.

It is not a de Polignac number, because 209813 - 2² = 209809 is a prime.

It is a d-powerful number, because it can be written as 2¹⁷ + 0 + 8 + 9⁵ + 1 + 3⁹ .

It is a plaindrome in base 11 and base 14.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104906 + 104907.

It is an arithmetic number, because the mean of its divisors is an integer number (104907).

2²⁰⁹⁸¹³ is an apocalyptic number.

It is an amenable number.

209813 is a deficient number, since it is larger than the sum of its proper divisors (1).

209813 is an equidigital number, since it uses as much as digits as its factorization.

209813 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 209813 is about 458.0534903262. The cubic root of 209813 is about 59.4215712182.

The spelling of 209813 in words is "two hundred nine thousand, eight hundred thirteen".