209213581 has 2 divisors, whose sum is σ = 209213582. Its totient is φ = 209213580.

The previous prime is 209213561. The next prime is 209213603. The reversal of 209213581 is 185312902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 161036100 + 48177481 = 12690^2 + 6941^2 .

It is a cyclic number.

It is not a de Polignac number, because 209213581 - 2⁵ = 209213549 is a prime.

It is a super-2 number, since 2×209213581² = 87540644949687122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209213551) 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, 104606790 + 104606791.

It is an arithmetic number, because the mean of its divisors is an integer number (104606791).

Almost surely, 2^209213581 is an apocalyptic number.

It is an amenable number.

209213581 is a deficient number, since it is larger than the sum of its proper divisors (1).

209213581 is an equidigital number, since it uses as much as digits as its factorization.

209213581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 209213581 is about 14464.2172619192. The cubic root of 209213581 is about 593.6492968122.

The spelling of 209213581 in words is "two hundred nine million, two hundred thirteen thousand, five hundred eighty-one".