261705617 has 4 divisors (see below), whose sum is σ = 262050276. Its totient is φ = 261360960.

The previous prime is 261705607. The next prime is 261705623. The reversal of 261705617 is 716507162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45144961 + 216560656 = 6719^2 + 14716^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261705617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261705607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 171188 + ... + 172709.

It is an arithmetic number, because the mean of its divisors is an integer number (65512569).

Almost surely, 2^261705617 is an apocalyptic number.

It is an amenable number.

261705617 is a deficient number, since it is larger than the sum of its proper divisors (344659).

261705617 is an equidigital number, since it uses as much as digits as its factorization.

261705617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344658.

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 261705617 is about 16177.3179791954. The cubic root of 261705617 is about 639.6430439483.

The spelling of 261705617 in words is "two hundred sixty-one million, seven hundred five thousand, six hundred seventeen".