263661 has 4 divisors (see below), whose sum is σ = 351552. Its totient is φ = 175772.

The previous prime is 263657. The next prime is 263677. The reversal of 263661 is 166362.

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.

It is a cyclic number.

It is not a de Polignac number, because 263661 - 2² = 263657 is a prime.

It is a D-number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 263661.

It is not an unprimeable number, because it can be changed into a prime (263611) 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, 43941 + ... + 43946.

It is an arithmetic number, because the mean of its divisors is an integer number (87888).

2²⁶³⁶⁶¹ is an apocalyptic number.

It is an amenable number.

263661 is a deficient number, since it is larger than the sum of its proper divisors (87891).

263661 is an equidigital number, since it uses as much as digits as its factorization.

263661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87890.

The product of its digits is 1296, while the sum is 24.

The square root of 263661 is about 513.4793082491. The cubic root of 263661 is about 64.1232164007.

The spelling of 263661 in words is "two hundred sixty-three thousand, six hundred sixty-one".