261310817 has 4 divisors (see below), whose sum is σ = 261343236. Its totient is φ = 261278400.

The previous prime is 261310801. The next prime is 261310837. The reversal of 261310817 is 718013162.

261310817 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 120912016 + 140398801 = 10996^2 + 11849^2 .

It is a cyclic number.

It is not a de Polignac number, because 261310817 - 2⁴ = 261310801 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261310817.

It is not an unprimeable number, because it can be changed into a prime (261310837) 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, 6317 + ... + 23717.

It is an arithmetic number, because the mean of its divisors is an integer number (65335809).

Almost surely, 2^261310817 is an apocalyptic number.

It is an amenable number.

261310817 is a deficient number, since it is larger than the sum of its proper divisors (32419).

261310817 is a wasteful number, since it uses less digits than its factorization.

261310817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32418.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 261310817 is about 16165.1111038557. Note that the first 4 decimals coincide. The cubic root of 261310817 is about 639.3212343138.

Adding to 261310817 its reverse (718013162), we get a palindrome (979323979).

The spelling of 261310817 in words is "two hundred sixty-one million, three hundred ten thousand, eight hundred seventeen".