245561 has 2 divisors, whose sum is σ = 245562. Its totient is φ = 245560.

The previous prime is 245533. The next prime is 245563. The reversal of 245561 is 165542.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219961 + 25600 = 469^2 + 160^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-245561 is a prime.

Together with 245563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (245563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 122780 + 122781.

It is an arithmetic number, because the mean of its divisors is an integer number (122781).

2²⁴⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

245561 is a deficient number, since it is larger than the sum of its proper divisors (1).

245561 is an equidigital number, since it uses as much as digits as its factorization.

245561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1200, while the sum is 23.

The square root of 245561 is about 495.5411183747. The cubic root of 245561 is about 62.6209710384.

The spelling of 245561 in words is "two hundred forty-five thousand, five hundred sixty-one".