215139209 has 2 divisors, whose sum is σ = 215139210. Its totient is φ = 215139208.

The previous prime is 215139203. The next prime is 215139241. The reversal of 215139209 is 902931512.

It is an a-pointer prime, because the next prime (215139241) can be obtained adding 215139209 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 208889209 + 6250000 = 14453^2 + 2500^2 .

It is a cyclic number.

It is not a de Polignac number, because 215139209 - 2¹² = 215135113 is a prime.

It is not a weakly prime, because it can be changed into another prime (215139203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107569604 + 107569605.

It is an arithmetic number, because the mean of its divisors is an integer number (107569605).

Almost surely, 2^215139209 is an apocalyptic number.

It is an amenable number.

215139209 is a deficient number, since it is larger than the sum of its proper divisors (1).

215139209 is an equidigital number, since it uses as much as digits as its factorization.

215139209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4860, while the sum is 32.

The square root of 215139209 is about 14667.6245179647. The cubic root of 215139209 is about 599.2019101881.

The spelling of 215139209 in words is "two hundred fifteen million, one hundred thirty-nine thousand, two hundred nine".