646974161 has 2 divisors, whose sum is σ = 646974162. Its totient is φ = 646974160.

The previous prime is 646974157. The next prime is 646974169. The reversal of 646974161 is 161479646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 643890625 + 3083536 = 25375^2 + 1756^2 .

It is a cyclic number.

It is not a de Polignac number, because 646974161 - 2² = 646974157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (646974169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323487080 + 323487081.

It is an arithmetic number, because the mean of its divisors is an integer number (323487081).

Almost surely, 2^646974161 is an apocalyptic number.

It is an amenable number.

646974161 is a deficient number, since it is larger than the sum of its proper divisors (1).

646974161 is an equidigital number, since it uses as much as digits as its factorization.

646974161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 44.

The square root of 646974161 is about 25435.6867609271. The cubic root of 646974161 is about 864.8928603087.

The spelling of 646974161 in words is "six hundred forty-six million, nine hundred seventy-four thousand, one hundred sixty-one".