671423561 has 2 divisors, whose sum is σ = 671423562. Its totient is φ = 671423560.

The previous prime is 671423509. The next prime is 671423563. The reversal of 671423561 is 165324176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637259536 + 34164025 = 25244^2 + 5845^2 .

It is a cyclic number.

It is not a de Polignac number, because 671423561 - 2²² = 667229257 is a prime.

Together with 671423563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (671423563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 335711780 + 335711781.

It is an arithmetic number, because the mean of its divisors is an integer number (335711781).

Almost surely, 2^671423561 is an apocalyptic number.

It is an amenable number.

671423561 is a deficient number, since it is larger than the sum of its proper divisors (1).

671423561 is an equidigital number, since it uses as much as digits as its factorization.

671423561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 35.

The square root of 671423561 is about 25911.8420997041. The cubic root of 671423561 is about 875.6533073605.

The spelling of 671423561 in words is "six hundred seventy-one million, four hundred twenty-three thousand, five hundred sixty-one".