671742661 has 2 divisors, whose sum is σ = 671742662. Its totient is φ = 671742660.

The previous prime is 671742649. The next prime is 671742679. The reversal of 671742661 is 166247176.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 668481025 + 3261636 = 25855^2 + 1806^2 .

It is a cyclic number.

It is not a de Polignac number, because 671742661 - 2²⁹ = 134871749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (671742601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335871330 + 335871331.

It is an arithmetic number, because the mean of its divisors is an integer number (335871331).

Almost surely, 2^671742661 is an apocalyptic number.

It is an amenable number.

671742661 is a deficient number, since it is larger than the sum of its proper divisors (1).

671742661 is an equidigital number, since it uses as much as digits as its factorization.

671742661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 40.

The square root of 671742661 is about 25917.9987846284. The cubic root of 671742661 is about 875.7920060561.

The spelling of 671742661 in words is "six hundred seventy-one million, seven hundred forty-two thousand, six hundred sixty-one".