645694725877 has 2 divisors, whose sum is σ = 645694725878. Its totient is φ = 645694725876.

The previous prime is 645694725857. The next prime is 645694725887. The reversal of 645694725877 is 778527496546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 547258173361 + 98436552516 = 739769^2 + 313746^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645694725877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645694725857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322847362938 + 322847362939.

It is an arithmetic number, because the mean of its divisors is an integer number (322847362939).

Almost surely, 2^645694725877 is an apocalyptic number.

It is an amenable number.

645694725877 is a deficient number, since it is larger than the sum of its proper divisors (1).

645694725877 is an equidigital number, since it uses as much as digits as its factorization.

645694725877 is an evil number, because the sum of its binary digits is even.

The product of its digits is 711244800, while the sum is 70.

The spelling of 645694725877 in words is "six hundred forty-five billion, six hundred ninety-four million, seven hundred twenty-five thousand, eight hundred seventy-seven".