261488609 has 2 divisors, whose sum is σ = 261488610. Its totient is φ = 261488608.

The previous prime is 261488597. The next prime is 261488641. The reversal of 261488609 is 906884162.

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., 245862400 + 15626209 = 15680^2 + 3953^2 .

It is a cyclic number.

It is not a de Polignac number, because 261488609 - 2¹⁶ = 261423073 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261488609.

It is not a weakly prime, because it can be changed into another prime (261488699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130744304 + 130744305.

It is an arithmetic number, because the mean of its divisors is an integer number (130744305).

Almost surely, 2^261488609 is an apocalyptic number.

It is an amenable number.

261488609 is a deficient number, since it is larger than the sum of its proper divisors (1).

261488609 is an equidigital number, since it uses as much as digits as its factorization.

261488609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 165888, while the sum is 44.

The square root of 261488609 is about 16170.6094195612. The cubic root of 261488609 is about 639.4661963339.

The spelling of 261488609 in words is "two hundred sixty-one million, four hundred eighty-eight thousand, six hundred nine".