646571 has 2 divisors, whose sum is σ = 646572. Its totient is φ = 646570.

The previous prime is 646549. The next prime is 646573. The reversal of 646571 is 175646.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646571 is a prime.

Together with 646573, 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 (646573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323285 + 323286.

It is an arithmetic number, because the mean of its divisors is an integer number (323286).

2⁶⁴⁶⁵⁷¹ is an apocalyptic number.

646571 is a deficient number, since it is larger than the sum of its proper divisors (1).

646571 is an equidigital number, since it uses as much as digits as its factorization.

646571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 29.

The square root of 646571 is about 804.0963872571. The cubic root of 646571 is about 86.4713170740.

The spelling of 646571 in words is "six hundred forty-six thousand, five hundred seventy-one".