263591561 has 2 divisors, whose sum is σ = 263591562. Its totient is φ = 263591560.

The previous prime is 263591551. The next prime is 263591599. The reversal of 263591561 is 165195362.

It is an a-pointer prime, because the next prime (263591599) can be obtained adding 263591561 to its sum of digits (38).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255360400 + 8231161 = 15980^2 + 2869^2 .

It is a cyclic number.

It is not a de Polignac number, because 263591561 - 2¹⁴ = 263575177 is a prime.

It is a super-2 number, since 2×263591561² = 138961022060833442, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (263591521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 131795780 + 131795781.

It is an arithmetic number, because the mean of its divisors is an integer number (131795781).

Almost surely, 2^263591561 is an apocalyptic number.

It is an amenable number.

263591561 is a deficient number, since it is larger than the sum of its proper divisors (1).

263591561 is an equidigital number, since it uses as much as digits as its factorization.

263591561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48600, while the sum is 38.

The square root of 263591561 is about 16235.5031027683. The cubic root of 263591561 is about 641.1758664253.

The spelling of 263591561 in words is "two hundred sixty-three million, five hundred ninety-one thousand, five hundred sixty-one".