671788781 has 2 divisors, whose sum is σ = 671788782. Its totient is φ = 671788780.

The previous prime is 671788771. The next prime is 671788823. The reversal of 671788781 is 187887176.

671788781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 656896900 + 14891881 = 25630^2 + 3859^2 .

It is a cyclic number.

It is not a de Polignac number, because 671788781 - 2⁶ = 671788717 is a prime.

It is a super-2 number, since 2×671788781² = 902600332554931922, which contains 22 as substring.

It is a Sophie Germain prime.

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 (671788721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335894390 + 335894391.

It is an arithmetic number, because the mean of its divisors is an integer number (335894391).

Almost surely, 2^671788781 is an apocalyptic number.

It is an amenable number.

671788781 is a deficient number, since it is larger than the sum of its proper divisors (1).

671788781 is an equidigital number, since it uses as much as digits as its factorization.

671788781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1053696, while the sum is 53.

The square root of 671788781 is about 25918.8884985448. Note that the first 3 decimals coincide. The cubic root of 671788781 is about 875.8120487526.

The spelling of 671788781 in words is "six hundred seventy-one million, seven hundred eighty-eight thousand, seven hundred eighty-one".