645463561 has 2 divisors, whose sum is σ = 645463562. Its totient is φ = 645463560.

The previous prime is 645463547. The next prime is 645463589. The reversal of 645463561 is 165364546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 634032400 + 11431161 = 25180^2 + 3381^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645463561 is a prime.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (645463061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322731780 + 322731781.

It is an arithmetic number, because the mean of its divisors is an integer number (322731781).

Almost surely, 2^645463561 is an apocalyptic number.

It is an amenable number.

645463561 is a deficient number, since it is larger than the sum of its proper divisors (1).

645463561 is an equidigital number, since it uses as much as digits as its factorization.

645463561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 259200, while the sum is 40.

The square root of 645463561 is about 25405.9749074898. The cubic root of 645463561 is about 864.2191985173.

The spelling of 645463561 in words is "six hundred forty-five million, four hundred sixty-three thousand, five hundred sixty-one".