646181 has 2 divisors, whose sum is σ = 646182. Its totient is φ = 646180.

The previous prime is 646169. The next prime is 646183. The reversal of 646181 is 181646.

646181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 429025 + 217156 = 655^2 + 466^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646181 is a prime.

It is a super-2 number, since 2×646181² = 835099769522, which contains 22 as substring.

Together with 646183, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 646181.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646181.

It is not a weakly prime, because it can be changed into another prime (646183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323090 + 323091.

It is an arithmetic number, because the mean of its divisors is an integer number (323091).

2⁶⁴⁶¹⁸¹ is an apocalyptic number.

It is an amenable number.

646181 is a deficient number, since it is larger than the sum of its proper divisors (1).

646181 is an equidigital number, since it uses as much as digits as its factorization.

646181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 26.

The square root of 646181 is about 803.8538424365. The cubic root of 646181 is about 86.4539275960.

The spelling of 646181 in words is "six hundred forty-six thousand, one hundred eighty-one".