263311561 has 8 divisors (see below), whose sum is σ = 272709000. Its totient is φ = 253935360.

The previous prime is 263311549. The next prime is 263311577. The reversal of 263311561 is 165113362.

It can be written as a sum of positive squares in 4 ways, for example, as 14776336 + 248535225 = 3844^2 + 15765^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 263311561 - 2²¹ = 261214409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (263311501) 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, 22465 + ... + 32113.

It is an arithmetic number, because the mean of its divisors is an integer number (34088625).

Almost surely, 2^263311561 is an apocalyptic number.

It is an amenable number.

263311561 is a deficient number, since it is larger than the sum of its proper divisors (9397439).

263311561 is an equidigital number, since it uses as much as digits as its factorization.

263311561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10619.

The product of its digits is 3240, while the sum is 28.

The square root of 263311561 is about 16226.8777341792. The cubic root of 263311561 is about 640.9487564125.

The spelling of 263311561 in words is "two hundred sixty-three million, three hundred eleven thousand, five hundred sixty-one".