671286778817 has 2 divisors, whose sum is σ = 671286778818. Its totient is φ = 671286778816.

The previous prime is 671286778661. The next prime is 671286778823. The reversal of 671286778817 is 718877682176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 479478693136 + 191808085681 = 692444^2 + 437959^2 .

It is a cyclic number.

It is not a de Polignac number, because 671286778817 - 2³⁶ = 602567302081 is a prime.

It is not a weakly prime, because it can be changed into another prime (671286778837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335643389408 + 335643389409.

It is an arithmetic number, because the mean of its divisors is an integer number (335643389409).

Almost surely, 2^671286778817 is an apocalyptic number.

It is an amenable number.

671286778817 is a deficient number, since it is larger than the sum of its proper divisors (1).

671286778817 is an equidigital number, since it uses as much as digits as its factorization.

671286778817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 88510464, while the sum is 68.

The spelling of 671286778817 in words is "six hundred seventy-one billion, two hundred eighty-six million, seven hundred seventy-eight thousand, eight hundred seventeen".