261609241 has 2 divisors, whose sum is σ = 261609242. Its totient is φ = 261609240.

The previous prime is 261609239. The next prime is 261609247. The reversal of 261609241 is 142906162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 240126016 + 21483225 = 15496^2 + 4635^2 .

It is a cyclic number.

It is not a de Polignac number, because 261609241 - 2¹ = 261609239 is a prime.

Together with 261609239, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261609247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130804620 + 130804621.

It is an arithmetic number, because the mean of its divisors is an integer number (130804621).

Almost surely, 2^261609241 is an apocalyptic number.

It is an amenable number.

261609241 is a deficient number, since it is larger than the sum of its proper divisors (1).

261609241 is an equidigital number, since it uses as much as digits as its factorization.

261609241 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 261609241 is about 16174.3389663998. The cubic root of 261609241 is about 639.5645157562.

The spelling of 261609241 in words is "two hundred sixty-one million, six hundred nine thousand, two hundred forty-one".