261579609 has 18 divisors (see below), whose sum is σ = 381896190. Its totient is φ = 172532736.

The previous prime is 261579607. The next prime is 261579611. The reversal of 261579609 is 906975162.

It is a happy number.

261579609 is a `hidden beast` number, since 26 + 15 + 7 + 9 + 609 = 666.

It is an interprime number because it is at equal distance from previous prime (261579607) and next prime (261579611).

It can be written as a sum of positive squares in 3 ways, for example, as 80946009 + 180633600 = 8997^2 + 13440^2 .

It is not a de Polignac number, because 261579609 - 2¹ = 261579607 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261579607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 83137 + ... + 86225.

It is an arithmetic number, because the mean of its divisors is an integer number (21216455).

Almost surely, 2^261579609 is an apocalyptic number.

It is an amenable number.

261579609 is a deficient number, since it is larger than the sum of its proper divisors (120316581).

261579609 is an equidigital number, since it uses as much as digits as its factorization.

261579609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3289 (or 3189 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 45.

The square root of 261579609 is about 16173.4229215711. The cubic root of 261579609 is about 639.5403674103.

The spelling of 261579609 in words is "two hundred sixty-one million, five hundred seventy-nine thousand, six hundred nine".