671696981 has 2 divisors, whose sum is σ = 671696982. Its totient is φ = 671696980.

The previous prime is 671696969. The next prime is 671696983. The reversal of 671696981 is 189696176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 569585956 + 102111025 = 23866^2 + 10105^2 .

It is a cyclic number.

It is not a de Polignac number, because 671696981 - 2¹⁰ = 671695957 is a prime.

It is a super-2 number, since 2×671696981² = 902353668569028722, which contains 22 as substring.

Together with 671696983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (671696983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335848490 + 335848491.

It is an arithmetic number, because the mean of its divisors is an integer number (335848491).

Almost surely, 2^671696981 is an apocalyptic number.

It is an amenable number.

671696981 is a deficient number, since it is larger than the sum of its proper divisors (1).

671696981 is an equidigital number, since it uses as much as digits as its factorization.

671696981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 53.

The square root of 671696981 is about 25917.1175287685. The cubic root of 671696981 is about 875.7721536691.

The spelling of 671696981 in words is "six hundred seventy-one million, six hundred ninety-six thousand, nine hundred eighty-one".