646630181 has 2 divisors, whose sum is σ = 646630182. Its totient is φ = 646630180.

The previous prime is 646630177. The next prime is 646630223. The reversal of 646630181 is 181036646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 331567681 + 315062500 = 18209^2 + 17750^2 .

It is a cyclic number.

It is not a de Polignac number, because 646630181 - 2² = 646630177 is a prime.

It is a super-2 number, since 2×646630181² = 836261181960185522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646630151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323315090 + 323315091.

It is an arithmetic number, because the mean of its divisors is an integer number (323315091).

Almost surely, 2^646630181 is an apocalyptic number.

It is an amenable number.

646630181 is a deficient number, since it is larger than the sum of its proper divisors (1).

646630181 is an equidigital number, since it uses as much as digits as its factorization.

646630181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 646630181 is about 25428.9241022895. The cubic root of 646630181 is about 864.7395524926.

The spelling of 646630181 in words is "six hundred forty-six million, six hundred thirty thousand, one hundred eighty-one".