261603 has 8 divisors (see below), whose sum is σ = 387600. Its totient is φ = 174384.

The previous prime is 261601. The next prime is 261619. The reversal of 261603 is 306162.

It is a happy number.

261603 is a `hidden beast` number, since 2 + 61 + 603 = 666.

It is not a de Polignac number, because 261603 - 2¹ = 261601 is a prime.

It is a super-2 number, since 2×261603² = 136872259218, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4818 + ... + 4871.

It is an arithmetic number, because the mean of its divisors is an integer number (48450).

2²⁶¹⁶⁰³ is an apocalyptic number.

261603 is a deficient number, since it is larger than the sum of its proper divisors (125997).

261603 is an equidigital number, since it uses as much as digits as its factorization.

261603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9698 (or 9692 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 261603 is about 511.4714068254. The cubic root of 261603 is about 63.9559429858.

Adding to 261603 its reverse (306162), we get a palindrome (567765).

The spelling of 261603 in words is "two hundred sixty-one thousand, six hundred three".