215309 has 2 divisors, whose sum is σ = 215310. Its totient is φ = 215308.

The previous prime is 215297. The next prime is 215317. The reversal of 215309 is 903512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162409 + 52900 = 403^2 + 230^2 .

It is a cyclic number.

It is not a de Polignac number, because 215309 - 2¹² = 211213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107654 + 107655.

It is an arithmetic number, because the mean of its divisors is an integer number (107655).

2²¹⁵³⁰⁹ is an apocalyptic number.

It is an amenable number.

215309 is a deficient number, since it is larger than the sum of its proper divisors (1).

215309 is an equidigital number, since it uses as much as digits as its factorization.

215309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 270, while the sum is 20.

The square root of 215309 is about 464.0140084092. The cubic root of 215309 is about 59.9359501698.

The spelling of 215309 in words is "two hundred fifteen thousand, three hundred nine".