320065561 has 2 divisors, whose sum is σ = 320065562. Its totient is φ = 320065560.

The previous prime is 320065553. The next prime is 320065573. The reversal of 320065561 is 165560023.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 305165961 + 14899600 = 17469^2 + 3860^2 .

It is an emirp because it is prime and its reverse (165560023) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 320065561 - 2³ = 320065553 is a prime.

It is a super-3 number, since 3×320065561³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (320065531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160032780 + 160032781.

It is an arithmetic number, because the mean of its divisors is an integer number (160032781).

Almost surely, 2^320065561 is an apocalyptic number.

It is an amenable number.

320065561 is a deficient number, since it is larger than the sum of its proper divisors (1).

320065561 is an equidigital number, since it uses as much as digits as its factorization.

320065561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 320065561 is about 17890.3762118073. The cubic root of 320065561 is about 684.0370870364.

The spelling of 320065561 in words is "three hundred twenty million, sixty-five thousand, five hundred sixty-one".