645717461 has 2 divisors, whose sum is σ = 645717462. Its totient is φ = 645717460.

The previous prime is 645717437. The next prime is 645717463. The reversal of 645717461 is 164717546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 334194961 + 311522500 = 18281^2 + 17650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645717461 is a prime.

It is a Sophie Germain prime.

Together with 645717463, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645717463) 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, 322858730 + 322858731.

It is an arithmetic number, because the mean of its divisors is an integer number (322858731).

Almost surely, 2^645717461 is an apocalyptic number.

It is an amenable number.

645717461 is a deficient number, since it is larger than the sum of its proper divisors (1).

645717461 is an equidigital number, since it uses as much as digits as its factorization.

645717461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 141120, while the sum is 41.

The square root of 645717461 is about 25410.9712722674. The cubic root of 645717461 is about 864.3325002862.

The spelling of 645717461 in words is "six hundred forty-five million, seven hundred seventeen thousand, four hundred sixty-one".