261617 has 4 divisors (see below), whose sum is σ = 262656. Its totient is φ = 260580.

The previous prime is 261601. The next prime is 261619. The reversal of 261617 is 716162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 261617 - 2⁴ = 261601 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261592 and 261601.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 261617.

It is not an unprimeable number, because it can be changed into a prime (261619) 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, 128 + ... + 734.

It is an arithmetic number, because the mean of its divisors is an integer number (65664).

2²⁶¹⁶¹⁷ is an apocalyptic number.

It is an amenable number.

261617 is a deficient number, since it is larger than the sum of its proper divisors (1039).

261617 is an equidigital number, since it uses as much as digits as its factorization.

261617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1038.

The product of its digits is 504, while the sum is 23.

The square root of 261617 is about 511.4850926469. The cubic root of 261617 is about 63.9570838586.

Adding to 261617 its reverse (716162), we get a palindrome (977779).

It can be divided in two parts, 261 and 617, that added together give a palindrome (878).

The spelling of 261617 in words is "two hundred sixty-one thousand, six hundred seventeen".