671815325981 has 2 divisors, whose sum is σ = 671815325982. Its totient is φ = 671815325980.

The previous prime is 671815325963. The next prime is 671815325989. The reversal of 671815325981 is 189523518176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 560613085081 + 111202240900 = 748741^2 + 333470^2 .

It is a cyclic number.

It is not a de Polignac number, because 671815325981 - 2³⁸ = 396937419037 is a prime.

It is a super-2 number, since 2×671815325981² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (671815325989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335907662990 + 335907662991.

It is an arithmetic number, because the mean of its divisors is an integer number (335907662991).

Almost surely, 2^671815325981 is an apocalyptic number.

It is an amenable number.

671815325981 is a deficient number, since it is larger than the sum of its proper divisors (1).

671815325981 is an equidigital number, since it uses as much as digits as its factorization.

671815325981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3628800, while the sum is 56.

The spelling of 671815325981 in words is "six hundred seventy-one billion, eight hundred fifteen million, three hundred twenty-five thousand, nine hundred eighty-one".