645463661 has 2 divisors, whose sum is σ = 645463662. Its totient is φ = 645463660.

The previous prime is 645463619. The next prime is 645463673. The reversal of 645463661 is 166364546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 593896900 + 51566761 = 24370^2 + 7181^2 .

It is a cyclic number.

It is not a de Polignac number, because 645463661 - 2²⁶ = 578354797 is a prime.

It is a Chen prime.

It is a congruent number.

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

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322731830 + 322731831.

It is an arithmetic number, because the mean of its divisors is an integer number (322731831).

Almost surely, 2^645463661 is an apocalyptic number.

It is an amenable number.

645463661 is a deficient number, since it is larger than the sum of its proper divisors (1).

645463661 is an equidigital number, since it uses as much as digits as its factorization.

645463661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 41.

The square root of 645463661 is about 25405.9768755307. The cubic root of 645463661 is about 864.2192431477.

The spelling of 645463661 in words is "six hundred forty-five million, four hundred sixty-three thousand, six hundred sixty-one".