645020756671 has 2 divisors, whose sum is σ = 645020756672. Its totient is φ = 645020756670.

The previous prime is 645020756617. The next prime is 645020756707. The reversal of 645020756671 is 176657020546.

Together with previous prime (645020756617) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645020756671 - 2³⁷ = 507581803199 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645020756371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322510378335 + 322510378336.

It is an arithmetic number, because the mean of its divisors is an integer number (322510378336).

Almost surely, 2^645020756671 is an apocalyptic number.

645020756671 is a deficient number, since it is larger than the sum of its proper divisors (1).

645020756671 is an equidigital number, since it uses as much as digits as its factorization.

645020756671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2116800, while the sum is 49.

The spelling of 645020756671 in words is "six hundred forty-five billion, twenty million, seven hundred fifty-six thousand, six hundred seventy-one".