320561 has 2 divisors, whose sum is σ = 320562. Its totient is φ = 320560.

The previous prime is 320539. The next prime is 320563. The reversal of 320561 is 165023.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255025 + 65536 = 505^2 + 256^2 .

It is a cyclic number.

It is not a de Polignac number, because 320561 - 2¹⁸ = 58417 is a prime.

Together with 320563, it forms a pair of twin primes.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 320561.

It is not a weakly prime, because it can be changed into another prime (320563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160280 + 160281.

It is an arithmetic number, because the mean of its divisors is an integer number (160281).

2³²⁰⁵⁶¹ is an apocalyptic number.

It is an amenable number.

320561 is a deficient number, since it is larger than the sum of its proper divisors (1).

320561 is an equidigital number, since it uses as much as digits as its factorization.

320561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 320561 is about 566.1810664443. The cubic root of 320561 is about 68.4389852197.

Adding to 320561 its reverse (165023), we get a palindrome (485584).

The spelling of 320561 in words is "three hundred twenty thousand, five hundred sixty-one".