209381 has 2 divisors, whose sum is σ = 209382. Its totient is φ = 209380.

The previous prime is 209371. The next prime is 209393. The reversal of 209381 is 183902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 188356 + 21025 = 434^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 209381 - 2⁶ = 209317 is a prime.

It is a super-2 number, since 2×209381² = 87680806322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104690 + 104691.

It is an arithmetic number, because the mean of its divisors is an integer number (104691).

2²⁰⁹³⁸¹ is an apocalyptic number.

It is an amenable number.

209381 is a deficient number, since it is larger than the sum of its proper divisors (1).

209381 is an equidigital number, since it uses as much as digits as its factorization.

209381 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 209381 is about 457.5816866965. The cubic root of 209381 is about 59.3807606599.

The spelling of 209381 in words is "two hundred nine thousand, three hundred eighty-one".