261159809 has 2 divisors, whose sum is σ = 261159810. Its totient is φ = 261159808.

The previous prime is 261159803. The next prime is 261159817. The reversal of 261159809 is 908951162.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 143328784 + 117831025 = 11972^2 + 10855^2 .

It is a cyclic number.

It is not a de Polignac number, because 261159809 - 2²⁰ = 260111233 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (261159803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130579904 + 130579905.

It is an arithmetic number, because the mean of its divisors is an integer number (130579905).

Almost surely, 2^261159809 is an apocalyptic number.

It is an amenable number.

261159809 is a deficient number, since it is larger than the sum of its proper divisors (1).

261159809 is an equidigital number, since it uses as much as digits as its factorization.

261159809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 261159809 is about 16160.4396289210. The cubic root of 261159809 is about 639.1980588748.

The spelling of 261159809 in words is "two hundred sixty-one million, one hundred fifty-nine thousand, eight hundred nine".