263561 has 2 divisors, whose sum is σ = 263562. Its totient is φ = 263560.

The previous prime is 263537. The next prime is 263567. The reversal of 263561 is 165362.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 198025 + 65536 = 445^2 + 256^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-263561 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an Ulam number.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (263567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 131780 + 131781.

It is an arithmetic number, because the mean of its divisors is an integer number (131781).

2²⁶³⁵⁶¹ is an apocalyptic number.

It is an amenable number.

263561 is a deficient number, since it is larger than the sum of its proper divisors (1).

263561 is an equidigital number, since it uses as much as digits as its factorization.

263561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 23.

The square root of 263561 is about 513.3819241072. The cubic root of 263561 is about 64.1151086000.

The spelling of 263561 in words is "two hundred sixty-three thousand, five hundred sixty-one".