645704257663 has 2 divisors, whose sum is σ = 645704257664. Its totient is φ = 645704257662.

The previous prime is 645704257589. The next prime is 645704257697. The reversal of 645704257663 is 366752407546.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645704257663 - 2¹³ = 645704249471 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645704287663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322852128831 + 322852128832.

It is an arithmetic number, because the mean of its divisors is an integer number (322852128832).

Almost surely, 2^645704257663 is an apocalyptic number.

645704257663 is a deficient number, since it is larger than the sum of its proper divisors (1).

645704257663 is an equidigital number, since it uses as much as digits as its factorization.

645704257663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25401600, while the sum is 55.

The spelling of 645704257663 in words is "six hundred forty-five billion, seven hundred four million, two hundred fifty-seven thousand, six hundred sixty-three".